child_process: flush consuming streams

Dave · rvagg · commit 7793c364fc59 · 2015-12-05T16:31:23.000+11:00
When a client calls read() with a nonzero argument on a Socket, that Socket sets this._consuming to true. It never sets this._consuming back to false. ChildProcess.flushStdio() currently doesn't flush any streams where _consuming is truthy. But, that means that it never flushes any stream that has ever been read from. This prevents a child process from ever closing if one of its streams has been read from, causing issue #4049. This commit allows consuming streams to be flushed, and the child process to emit a close event. Fixes: #4049 PR-URL: #4071 Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
diff --git a/lib/internal/child_process.js b/lib/internal/child_process.js
@@ -217,7 +217,7 @@ util.inherits(ChildProcess, EventEmitter);
 function flushStdio(subprocess) {
   if (subprocess.stdio == null) return;
   subprocess.stdio.forEach(function(stream, fd, stdio) {
-    if (!stream || !stream.readable || stream._consuming)
+    if (!stream || !stream.readable)
       return;
     stream.resume();
   });
diff --git a/test/parallel/test-child-process-flush-stdio.js b/test/parallel/test-child-process-flush-stdio.js
@@ -0,0 +1,17 @@
+'use strict';
+const cp = require('child_process');
+const common = require('../common');
+const assert = require('assert');
+
+const p = cp.spawn('echo');
+
+p.on('close', common.mustCall(function(code, signal) {
+  assert.strictEqual(code, 0);
+  assert.strictEqual(signal, null);
+}));
+
+p.stdout.read();
+
+setTimeout(function() {
+  p.kill();
+}, 100);
