concurrency

crystal/concurrency.md

@@ -0,0 +1,17 @@
+# Concurrency
+{id: concurrency}
+
+## Send and receive
+{id: send-and-receive}
+{i: Channel}
+{i: send}
+{i: receive}
+{i: spawn}
+
+![](examples/concurrency/send_receive.cr)
+
+## Concurrent HTTP request
+{id: concurrent-http-request}
+
+![](examples/concurrency/http_request.cr)
+

crystal/crystal.json

@@ -33,6 +33,7 @@
         "time.md",
         "http_client.md",
         "process.md",
+        "concurrency.md",
         "other.md"
     ]
 }

crystal/examples/concurrency/http_request.cr

@@ -0,0 +1,15 @@
+require "http/client"
+puts "before"
+ch = Channel(HTTP::Client::Response).new
+
+puts "before spawn"
+spawn do
+  puts "in spawn before send"
+  res = HTTP::Client.get "https://code-maven.com/"
+  ch.send res
+  puts "in spawn after send"
+end
+
+puts "before receive"
+res = ch.receive
+puts "received #{res.body.size} bytes including this row: #{res.body.lines.select(/<title>/)}"

crystal/examples/concurrency/send_receive.cr

@@ -0,0 +1,13 @@
+puts "before"
+ch = Channel(Int32).new
+
+puts "before spawn"
+spawn do
+  puts "in spawn before send"
+  ch.send 42
+  puts "in spawn after send"
+end
+
+puts "before receive"
+res = ch.receive
+puts "received #{res}"