Do not wait when the child process does not exist (#3832)

tests/swoole_runtime/proc/close_after_wait.phpt

@@ -0,0 +1,38 @@
+--TEST--
+swoole_runtime/proc: proc_close() after wait
+--SKIPIF--
+<?php require __DIR__ . '/../../include/skipif.inc'; ?>
+--FILE--
+<?php
+require __DIR__ . '/../../include/bootstrap.php';
+
+include_once dirname(__FILE__) . "/proc_open_pipes.inc";
+Swoole\Runtime::enableCoroutine();
+
+Co\run(function() {
+    $descriptorspec = array(
+        0 => array("pipe", "/dev/null"),
+        1 => array("pipe", "/dev/null"),
+        2 => array("pipe", "/dev/null")
+    );
+
+    $proc = proc_open('/bin/sleep 30', $descriptorspec, $pipes);
+    Assert::notEmpty($proc);
+    echo "wait begin\n";
+
+    go(function() use($proc) {
+        usleep(100000);
+        proc_terminate($proc);
+    });
+
+    $info = Co\System::wait();
+    Assert::notEmpty($info);
+    echo "wait end\n";
+    proc_close($proc);
+    echo "proc_close end\n";
+});
+?>
+--EXPECTF--
+wait begin
+wait end
+proc_close end

thirdparty/php/standard/proc_open.cc

@@ -153,9 +153,10 @@ static void proc_co_rsrc_dtor(zend_resource *rsrc)
         }
     }
 
-    if (proc->running)
-    {
-        swoole_coroutine_waitpid(proc->child, &wstatus, 0);
+    if (proc->running) {
+        if (::waitpid(proc->child, &wstatus, WNOHANG) == 0) {
+            swoole_coroutine_waitpid(proc->child, &wstatus, 0);
+        }
     }
     if (proc->wstatus)
     {