{"id":3873,"date":"2020-08-14T21:56:17","date_gmt":"2020-08-14T16:26:17","guid":{"rendered":"https:\/\/golangbyexamples.com\/?p=3873"},"modified":"2023-12-18T17:40:33","modified_gmt":"2023-12-18T12:10:33","slug":"channel-golang","status":"publish","type":"post","link":"https:\/\/golangbyexamples.com\/channel-golang\/","title":{"rendered":"Channel in Go (Golang)"},"content":{"rendered":"\n<p class=\"has-medium-font-size\">This is the&nbsp; chapter 24 of the golang comprehensive tutorial series. Refer to this link for other chapters of the series \u2013&nbsp;<a href=\"https:\/\/golangbyexamples.com\/golang-comprehensive-tutorial\/\">Golang Comprehensive Tutorial Series<\/a><\/p>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Next Tutorial<\/strong>&nbsp;\u2013&nbsp;<a href=\"https:\/\/golangbyexamples.com\/select-statement-golang\/\">Select Statement<\/a><br><strong>Previous Tutorial<\/strong>&nbsp;\u2013 <a href=\"https:\/\/golangbyexamples.com\/goroutines-golang\/\">Goroutines<\/a><\/p>\n\n\n\n<p class=\"has-medium-font-size\">Now let\u2019s check out the current tutorial. Below is the table of contents for current tutorial<\/p>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_17 counter-hierarchy counter-decimal ez-toc-light-blue\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" style=\"display: none;\"><i class=\"ez-toc-glyphicon ez-toc-icon-toggle\"><\/i><\/a><\/span><\/div>\n<nav><ul class=\"ez-toc-list ez-toc-list-level-1\"><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Overview\" title=\"Overview\">Overview<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Declaring_Channels\" title=\"Declaring Channels\">Declaring Channels<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Operations_on_Channel\" title=\"Operations on Channel\">Operations on Channel<\/a><ul class=\"ez-toc-list-level-2\"><li class=\"ez-toc-heading-level-2\"><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Send_Operation\" title=\"Send Operation\">Send Operation<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-2\"><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Receive_Operation\" title=\"Receive Operation\">Receive Operation<\/a><\/li><\/ul><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Channel_Direction\" title=\"Channel Direction\">Channel Direction<\/a><ul class=\"ez-toc-list-level-2\"><li class=\"ez-toc-heading-level-2\"><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Only_Send_Channel\" title=\"Only Send Channel\">Only Send Channel<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-2\"><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Only_Receive_Channel\" title=\"Only Receive Channel\">Only Receive Channel<\/a><\/li><\/ul><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Capacity_of_a_channel_using_cap_function\" title=\"Capacity of a channel using cap()&nbsp;function\">Capacity of a channel using cap()&nbsp;function<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Length_of_a_channel_using_len_function\" title=\"Length of a channel using len() function\">Length of a channel using len() function<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Close_operation_on_a_channel\" title=\"Close operation on a channel\">Close operation on a channel<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#For_range_loop_on_a_channel\" title=\"For range loop on a channel\">For range loop on a channel<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Nil_channel\" title=\"Nil channel\">Nil channel<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Summary_table\" title=\"Summary table\">Summary table<\/a><\/li><li class=\"ez-toc-page-1 ez-toc-heading-level-1\"><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/#Conclusion\" title=\"Conclusion\">Conclusion<\/a><\/li><\/ul><\/nav><\/div>\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Overview\"><\/span><strong>Overview<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">Channel is a data type in Go which provides synchrounization and communication between goroutines. They can be thought of as pipes which is used by goroutines to communicate. This communication between goroutines doesn&#8217;t require any explicit locks. Locks are internally managed by channel themselves. Channel along with goroutine makes the go programming language concurrent. So we can say that golang has two&nbsp; concurrency primitives:<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>Goroutine<\/strong>&nbsp;&#8211; lightweight independent execution to achieve concurrency\/parallelism.<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>Channels<\/strong> &#8211;&nbsp;provides synchronization and communication between goroutines.<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Declaring_Channels\"><\/span><strong>Declaring Channels<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">Each channel variable can hold data only of a particular type. Go uses special keyword <strong>chan<\/strong> while declaring a channel. Below is the format for declaring a channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">var variable_name chan type<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">This only declares a channel which can hold data of type <strong>&lt;type&gt;<\/strong> and it creates a nil channel as default value of a channel is nil. Let&#8217;s see a program to confirm this.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    var a chan int\n    fmt.Println(a)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">{nil}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">To define the channel we can use the inbuilt function <strong>make.&nbsp;<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    var a chan int\n    a = make(chan int)\n    fmt.Println(a)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">0xc0000240c0<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">On your machine it might give a different address as output.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">So what does make do here. A channel is internally represented by a <strong>hchan<\/strong> struct whose main elements are:<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">type hchan struct {\n    qcount   uint           \/\/ total data in the queue\n    dataqsiz uint           \/\/ size of the circular queue\n    buf      unsafe.Pointer \/\/ points to an array of dataqsiz elements\n    elemsize uint16\n    closed   uint32         \/\/ denotes weather channel is closed or not\n    elemtype *_type         \/\/ element type\n    sendx    uint           \/\/ send index\n    recvx    uint           \/\/ receive index\n    recvq    waitq          \/\/ list of recv waiters\n    sendq    waitq          \/\/ list of send waiters\n    lock     mutex\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">When using <strong>make<\/strong>, an instance of <strong>hchan<\/strong> struct is created and all the fields are initialized to their default values.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Operations_on_Channel\"><\/span><strong>Operations on Channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">There are two major operations which can be done on a channel&nbsp;<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Send<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Receive<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">Let&#8217;s look at each of it one by one<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Send_Operation\"><\/span><strong>Send Operation<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"has-medium-font-size\">The send operation is used to send data to the channel. Below is the format for sending to a channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch <- val<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">where<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>ch<\/strong> is the channel variable<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>val<\/strong> is what being sent to the channel<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">Note that data type of <strong>val<\/strong> and data type of channel should match.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Receive_Operation\"><\/span><strong>Receive Operation<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"has-medium-font-size\">The receive operation is used to read data from the channel. Below is the format for receiving from&nbsp; a channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">val := <- ch <\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">where<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>ch<\/strong> is the channel variable<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>val<\/strong> is a variable in which the read data from the channel will be stored.<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">Let's see an example of where we will send data from one goroutine and receive that data in another goroutine.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n    \"time\"\n)\n\nfunc main() {\n    ch := make(chan int)\n\n    fmt.Println(\"Sending value to channel\")\n    go send(ch)\n\n    fmt.Println(\"Receiving from channel\")\n    go receive(ch)\n\n    time.Sleep(time.Second * 1)\n}\n\nfunc send(ch chan int) {\n    ch <- 1\n}\n\nfunc receive(ch chan int) {\n    val := <-ch\n    fmt.Printf(\"Value Received=%d in receive function\\n\", val)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Sending value to channel\nReceiving from channel\nValue Received=1 in receive function<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In above program, we created a channel named <strong>ch<\/strong> whose data type is <strong>int<\/strong> which means that it can only transport date of type <strong>int<\/strong>. Function <strong>send()<\/strong> and <strong>receive() <\/strong>are started as a goroutine. We are sending data to the channel <strong>ch<\/strong> in send() goroutine and receiving data from <strong>ch<\/strong> in the receive() goroutine.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">A very important point to note about the receive operation is that a particular value sent to the channel can only be received once in any of the goroutine.&nbsp; As you can see there are no locks used in the goroutine while sending as well as receiving from the channel. Locks are internally managed by the channels and no explicit lock has to be used in the code.&nbsp;<br><\/p>\n\n\n\n<p class=\"has-medium-font-size\">By default when we create channel with make, it creates a unbuffered channel which essentially means that channel created cannot store any data. So any send on a channel is blocked until there is&nbsp; another goroutine to receive it. So in the <strong>send()<\/strong> function, this line will block<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch <- 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">until in <strong>receive()<\/strong> function the value is received<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">val := <-ch<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Also we have kept a timeout in the main function to allow both send and receive function to complete. If we don't have a timeout in the end of main function, then the program will exit and the two goroutine might not get scheduled.<\/p>\n\n\n\n<p class=\"has-medium-font-size\"><br>To illustrate blocking on send lets add a log after we send the value to channel <strong>ch<\/strong> in the <strong>send() <\/strong>function and a timeout in the<strong> receive()<\/strong> function before we receive value from <strong>ch<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n\t\"fmt\"\n\t\"time\"\n)\n\nfunc main() {\n\tch := make(chan int)\n\tgo send(ch)\n\tgo receive(ch)\n\ttime.Sleep(time.Second * 2)\n}\n\nfunc send(ch chan int) {\n\tch <- 1\n\tfmt.Println(\"Sending value to channel complete\")\n}\n\nfunc receive(ch chan int) {\n\ttime.Sleep(time.Second * 1)\n\tfmt.Println(\"Timeout finished\")\n\t_ = <-ch\n\treturn\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Timeout finished\nSending value to channel complete<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">The log<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Timeout finished<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">will always be before<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Sending value to channel complete<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Try out with changing to different values of timeout in the receive function . You will notice the above order always. This illustrates that send on an unbuffered channel is block until a receive happens on that channel in some other goroutine. The receive on a channel is also blocked unless there is another goroutine to send to that channel.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">To illustrate blocking on receive lets add a log after we receive the value in the recieve() function and a timeout in the send() function before we send value<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n\t\"fmt\"\n\t\"time\"\n)\n\nfunc main() {\n  ch := make(chan int)\n  go send(ch)\n\n  go receive(ch)\n  time.Sleep(time.Second * 2)\n}\n\nfunc send(ch chan int) {\n  time.Sleep(time.Second * 1)\n  fmt.Println(\"Timeout finished\")\n  ch <- 1\n}\n\nfunc receive(ch chan int) {\n  val := <-ch\n  fmt.Printf(\"Receiving Value from channel finished. Value received: %d\\n\", val)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Timeout finished\nReceiving Value from channel finished. Value received: 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In above program we added a timeout before sending to the channel.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">The log<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Timeout finished<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">will always be before<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Receiving Value from channel finished. Value received: 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Try out with changing to different values of timeout in the send() function . You will notice the above order always.&nbsp;This illustrates that receive on an unbuffered channel is block until a send happens on that channel in some other goroutine.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">We can also receive the value in the main function itself.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n)\n\nfunc main() {\n    ch := make(chan int)\n    fmt.Println(\"Sending value to channel start\")\n    go send(ch)\n    val := <-ch\n    fmt.Printf(\"Receiving Value from channel finished. Value received: %d\\n\", val)\n}\n\nfunc send(ch chan int) {\n    ch <- 1\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Sending value to channel start\nReceiving Value from channel finished. Value received: 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">We have seen the example of an unbuffered channel till now. Unbuffered channel does not have any storage hence for an unbuffered channel<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Send on a channel is block unless there is other goroutine to receive.<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Receive is block until there is other goroutine on the other side to send.<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">In Go you can also create a buffered channel. A buffered channel has some capacity to hold data hence for a buffered channel:<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Send on a buffer channel only blocks if the buffer is full<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Receive is only block is channel is empty<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">This is the syntax for creating a buffered channel using the make function<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">a = make(chan <type>, capacity)<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">The second argument specifies the capacity of the channel. Unbuffered channel is of zero capacity .That is why sending is block if there is no receiver and receiving is block if there is no sender for unbuffered channel.<br><\/p>\n\n\n\n<p class=\"has-medium-font-size\">Let's see a program for a buffered channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n)\n\nfunc main() {\n    ch := make(chan int, 1)\n    ch <- 1\n    fmt.Println(\"Sending value to channnel complete\")\n    val := <-ch\n    fmt.Printf(\"Receiving Value from channel finished. Value received: %d\\n\", val)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In above program we created a buffered channel of length 1 like this<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch := make(chan int, 1)<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">We are sending a value and receiving the same in the main goroutine. This is possible as send to a buffered channel is not blocked if the channel is not full. So below line doesn\u2019t block for a buffered channel.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch <- 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">The channel is created with a capacity of one. Hence sending to the channel is not blocked and the value is stored in the channel's buffer. So sending and receiving in the same goroutine is only possible for a buffered channel. Let's see two important points we mentioned above<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;Send on a channel is blocked when the channel is full<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;Receive on a channel is blocked when the channel is empty<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">&nbsp;Let's see a program for each<\/p>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Send on a channel is blocked when the channel is full<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n)\n\nfunc main() {\n    ch := make(chan int, 1)\n    ch <- 1\n    ch <- 1\n    fmt.Println(\"Sending value to channnel complete\")\n    val := <-ch\n    fmt.Printf(\"Receiving Value from channel finished. Value received: %d\\n\", val)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">fatal error: all goroutines are asleep - deadlock!<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In the above program we created a channel of capacity one.&nbsp; After that, we send one value to the channel and post that we send another value to the channel.<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch <- 1\nch <- 1<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">The second sent to the channel is blocked the because buffer is full and hence it results in a deadlock situation because the program cannot proceed and that is why as you can see the output is<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">fatal error: all goroutines are asleep - deadlock!<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Receive on a channel is blocked when the channel is empty<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n)\n\nfunc main() {\n    ch := make(chan int, 1)\n    ch <- 1\n    fmt.Println(\"Sending value to channnel complete\")\n    val := <-ch\n    val = <-ch\n    fmt.Printf(\"Receiving Value from channel finished. Value received: %d\\n\", val)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">fatal error: all goroutines are asleep - deadlock!<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In the above program as well we created a channel of capacity one, after that we send one value to the channel and after that, we receive one value from the channel.&nbsp; Then we tried a second receive from the channel and it resulted in a deadlock situation because the program cannot proceed as the channel is empty and there is nothing to receive. That is why you can see the output is<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">fatal error: all goroutines are asleep - deadlock!<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">This illustrates that the received is blocked if the channel buffer is empty<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Channel_Direction\"><\/span><strong>Channel Direction<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">So far we have seen bi-directional channels in which we can both send as well as receive data. It is also possible to create uni-directional channels in golang. A channel can be created to which we can only send data, as well as a channel, can be created from which we can only receive data. This is determined by the direction of the arrow of the channel.<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;A channel to which we can only send data.&nbsp;<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">This is the syntax for&nbsp; such a channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">chan<- int<\/code><\/pre>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>A channel from which we can only send data<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">This is the syntax for&nbsp; such a channel<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\"><-chan in<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Now the question is, why would you want to create a channel through to which you can only send data or from which we can only receive data.&nbsp; This comes in handy while passing the channel to a function where we want to restrict the&nbsp; function too either&nbsp; send the data or receiver rate<\/p>\n\n\n\n<p class=\"has-medium-font-size\">There are many ways in which a channel can be passed as a function argument. The direction of arrow for a channel specifies the direction of flow of data<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>chan<\/strong>&nbsp; :bidirectional channel (Both read and write)<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>chan &lt;-<\/strong>&nbsp; :only writing to channel<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li><strong>&lt;- chan<\/strong>&nbsp; :only reading from channel (input channel)&nbsp; &nbsp;&nbsp;<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Only_Send_Channel\"><\/span><strong>Only Send Channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Signature of the such a&nbsp; channel to which only you can send,&nbsp; will be like below when passed to a function as an argument.<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">func process(ch chan<- int){ \/\/doSomething }<\/code><\/pre>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>When trying to receive data from such a channel will give below error.<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">invalid operation: <-ch (receive from send-only type chan<- int)<\/code><\/pre>\n\n\n\n<p>Try uncommenting below line in the code to see the above error<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">s := <-ch<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Code:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\nimport \"fmt\"\nfunc main() {\n    ch := make(chan int, 3)\n    process(ch)\n    fmt.Println(<-ch)\n}\nfunc process(ch chan<- int) {\n    ch <- 2\n    \/\/s := <-ch\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output: <\/strong>2<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Only_Receive_Channel\"><\/span><strong>Only Receive Channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Signature of the such a&nbsp; channel from which you can only receive data, will be like below&nbsp; when passed to a function as an argument<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">func process(ch <-chan int){ \/\/doSomething }<\/code><\/pre>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>When trying to send data to such a channel will give below error.<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">invalid operation: ch <- 2 (send to receive-only type <-chan int)<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Try uncommenting below line in the code to see the above error<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">ch <- 2<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Code:<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\nimport \"fmt\"\nfunc main() {\n    ch := make(chan int, 3)\n    ch <- 2\n    process(ch)\n    fmt.Println()\n}\nfunc process(ch <-chan int) {\n    s := <-ch\n    fmt.Println(s)\n    \/\/ch <- 2\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output: <\/strong>2<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Capacity_of_a_channel_using_cap_function\"><\/span><strong>Capacity of a channel using cap()&nbsp;function<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">The capacity of a&nbsp;buffered channel is the number of elements which that channel can hold. Capacity refers to the size of the buffer of the channel.&nbsp;The capacity of the channel can be specified during the creation of the channel while using the make function. The second argument is the capacity<\/p>\n\n\n\n<p class=\"has-medium-font-size\">Capacity of unbuffered channel is always zero<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    ch := make(chan int, 3)\n    fmt.Printf(\"Capacity: %d\\n\", cap(ch))\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Capacity: 3<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In the above program we specified the capacity as 3 in the make function<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">make(chan int, 3)<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Length_of_a_channel_using_len_function\"><\/span><strong>Length of a channel using len() function<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">Builtin <strong>len()<\/strong> function can be used to get the length of a channel. The length of a channel is the number of elements that are already there in the channel. So length actually represents the number of elements queued in the buffer of the channel. Length of a channel is always less than or equal to the capacity of the channel.<\/p>\n\n\n\n<p class=\"has-medium-font-size\">Length of unbuffered channel is always zero<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n\tch := make(chan int, 3)\n\tch <- 5\n\tfmt.Printf(\"Len: %d\\n\", len(ch))\n\n\tch <- 6\n\tfmt.Printf(\"Len: %d\\n\", len(ch))\n\tch <- 7\n\tfmt.Printf(\"Len: %d\\n\", len(ch))\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Len: 1\nLen: 2\nLen: 3<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In the above code, the first created a channel of capacity 3.&nbsp; After that, we keep sending some value to the channel. As you can notice from your output that after each send operation to the length of channel increases by one as the length denotes the number of items in the buffer of the channel.<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Close_operation_on_a_channel\"><\/span><strong>Close operation on a channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">Close is an inbuilt function that can be used to close a channel. Closing of a channel means that no more data can we send to the channel.&nbsp; Channel is generally closed when all the data has been sent and there's no more data to be send.&nbsp;Let's see a program<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n    \"fmt\"\n    \"time\"\n)\n\nfunc main() {\n    ch := make(chan int)\n    go sum(ch, 3)\n    ch <- 2\n    ch <- 2\n    ch <- 2\n    close(ch)\n    time.Sleep(time.Second * 1)\n}\n\nfunc sum(ch chan int, len int) {\n    sum := 0\n    for i := 0; i < len; i++ {\n        sum += <-ch\n    }\n    fmt.Printf(\"Sum: %d\\n\", sum)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Sum: 6<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">&nbsp;In the above program, we created a channel.&nbsp; Then we called the <strong>sum<\/strong> function in a goroutine. In the main function, we send 3 values to the channel and after that, we closed the channel indicating that no more values can be sent to the channel. The <strong>sum<\/strong> function iterates over the channel using the for loop and calculates the sum value.<br>Sending on a close channel will cause a panic.&nbsp; <\/p>\n\n\n\n<p class=\"has-medium-font-size\">See the program below<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\nfunc main() {\n    ch := make(chan int)\n    close(ch)\n    ch <- 2\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">panic: send on closed channel<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Also closing a already closed channel will cause a panic<\/p>\n\n\n\n<p class=\"has-medium-font-size\">While receiving from a&nbsp; channel we can also use an additional variable to determine if the channel has been closed.&nbsp; Below is the syntax for the&nbsp; same<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">val,ok <- ch<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">The value of ok will be<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>True if the channel is not closed<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>False if the channel is closed<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\nimport (\n    \"fmt\"\n)\nfunc main() {\n    ch := make(chan int, 1)\n    ch <- 2\n    val, ok := <-ch\n    fmt.Printf(\"Val: %d OK: %t\\n\", val, ok)\n\n    close(ch)\n    val, ok = <-ch\n    fmt.Printf(\"Val: %d OK: %t\\n\", val, ok)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Val: 2 OK: true\nVal: 0 OK: false<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">In the above program created a channel of capacity one.&nbsp; Then we send one value to the channel.&nbsp; The <strong>ok<\/strong> variable in the first receive is true since the channel is not closed. The ok variable in the second&nbsp; receive is&nbsp; false because the channel is closed<\/p>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"For_range_loop_on_a_channel\"><\/span><strong>For range loop on a channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">For range loop can be used to receive data from the channel until it is closed.&nbsp;<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport (\n\t\"fmt\"\n\t\"time\"\n)\n\nfunc main() {\n\tch := make(chan int, 3)\n\tch <- 2\n\tch <- 2\n\tch <- 2\n\tclose(ch)\n\tgo sum(ch)\n\ttime.Sleep(time.Second * 1)\n}\n\nfunc sum(ch chan int) {\n\tsum := 0\n\tfor val := range ch {\n\t\tsum += val\n\t}\n\tfmt.Printf(\"Sum: %d\\n\", sum)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">Sum: 6<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">&nbsp;In the above program,&nbsp; we created a channel.&nbsp;&nbsp; In the main function the send three values to the channel and after that, we closed the channel. Then we called the sum function and we passed the channel to that function. In the sum function, we did a for range loop over the channel.&nbsp;&nbsp; &nbsp;After iterating over all the values in the channel the for range loop will exit&nbsp; since the channel is closed<\/p>\n\n\n\n<p class=\"has-medium-font-size\">Now the question which comes to the mind is that what happens if you don't close a channel in the main function.&nbsp; Try commenting the line in which they are closing the channel. Now run the program.&nbsp; It will also&nbsp; output&nbsp; deadlock because&nbsp; for range loop will never finish in the sum function<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">fatal error: all goroutines are asleep - deadlock!<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Nil_channel\"><\/span><strong>Nil channel<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">The zero value of the channel is nil.&nbsp;Hence only declaring a channel creates a nil channel as default zero value of the channel is nil.&nbsp;Let's see a program to demonstrate that<\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">package main\n\nimport \"fmt\"\n\nfunc main() {\n    var a chan int\n    fmt.Print(\"Default zero value of channel: \")\n    fmt.Println(a)\n}<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Output<\/strong><\/p>\n\n\n\n<pre class=\"wp-block-prismatic-blocks\"><code class=\"language-go\">nil<\/code><\/pre>\n\n\n\n<p class=\"has-medium-font-size\">Some points to note about nil channel<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;Sending to a&nbsp; nil channel blocks forever<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;Receiving from nil channel blocks forever<\/li>\n<\/ul>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>&nbsp;Closing a nil channel results in panic<\/li>\n<\/ul>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Summary_table\"><\/span><strong>Summary table<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">So far we have seen&nbsp;5 operations on a channel.&nbsp;&nbsp;<\/p>\n\n\n\n<ul class=\"has-medium-font-size wp-block-list\">\n<li>Send<\/li>\n\n\n\n<li>Receive<\/li>\n\n\n\n<li>Close<\/li>\n\n\n\n<li>Length<\/li>\n\n\n\n<li>Capacity<\/li>\n<\/ul>\n\n\n\n<p class=\"has-medium-font-size\">Let's&nbsp;see a summary table&nbsp;which shows the result of each operation on the different types of channel<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-regular\"><table class=\"has-background\" style=\"background-color:#e7f5fe\"><tbody><tr><td><strong>Command<\/strong><\/td><td><strong>Unbuffered Channel<\/strong><strong>(Not Closed and not nil)<\/strong><\/td><td><strong>Buffered Channel<\/strong><strong>(Not Closed and not nil)<\/strong><\/td><td><strong>Closed Channel<\/strong><\/td><td><strong>Nil Channel<\/strong><\/td><\/tr><tr><td>Send<\/td><td>Block if there is is no corresponding receiver otherwise success<\/td><td>Block if the channel is full otherwise success<\/td><td>Panic<\/td><td>Block forever<\/td><\/tr><tr><td>Receive<\/td><td>Block if there is no corresponding sender otherwise success<\/td><td>Block if the channel is empty otherwise success<\/td><td>Receives the default value of data type from the channel if channel is empty else&nbsp;&nbsp;receives the actual value<\/td><td>Block forever<\/td><\/tr><tr><td>Close<\/td><td>Success<\/td><td>Success<\/td><td>Panic<\/td><td>Panic<\/td><\/tr><tr><td>Length<\/td><td>0<\/td><td>Number of elements queued in the buffer of the channel<\/td><td>-0 if unbuffered channel-Number of elements queued in the buffer if buffered channel<\/td><td>0<\/td><\/tr><tr><td>Capacity<\/td><td>0<\/td><td>Size of the buffer of the channel<\/td><td>-0 if unbuffered channel-Size of the buffer if buffered channel<\/td><td>0<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h1 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Conclusion\"><\/span><strong>Conclusion<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h1>\n\n\n\n<p class=\"has-medium-font-size\">&nbsp;This is all about channels in golang .Hope you have liked the article. Please share feedback\/improvements\/mistakes in comments.&nbsp;<\/p>\n\n\n\n<p class=\"has-medium-font-size\"><strong>Next Tutorial<\/strong>&nbsp;\u2013&nbsp;<a href=\"https:\/\/golangbyexamples.com\/select-statement-golang\/\">Select Statement<\/a><br><strong>Previous Tutorial<\/strong>&nbsp;\u2013 <a href=\"https:\/\/golangbyexamples.com\/goroutines-golang\/\">Goroutines<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>This is the&nbsp; chapter 24 of the golang comprehensive tutorial series. Refer to this link for other chapters of the series \u2013&nbsp;Golang Comprehensive Tutorial Series Next Tutorial&nbsp;\u2013&nbsp;Select StatementPrevious Tutorial&nbsp;\u2013 Goroutines Now let\u2019s&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":"","footnotes":"","jetpack_publicize_message":"","jetpack_is_tweetstorm":false},"categories":[1],"tags":[3,4],"class_list":["post-3873","post","type-post","status-publish","format-standard","hentry","category-tech","tag-go","tag-golang"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.7 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Channel in Go (Golang) - Welcome To Golang By Example<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/golangbyexamples.com\/channel-golang\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Channel in Go (Golang) - Welcome To Golang By Example\" \/>\n<meta property=\"og:description\" content=\"This is the&nbsp; chapter 24 of the golang comprehensive tutorial series. 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