Fixed style and added regression test

deps/v8/src/sampler.cc

@@ -346,8 +346,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   // ISSUE-14576: To avoid deadlock, return if there is a thread lock
   if (Isolate::GetProcessWideMutex().Pointer()->TryLock()) {
     Isolate::GetProcessWideMutex().Pointer()->Unlock();
-  }
-  else {
+  } else {
     return;
   }
 

test/simple/test-regress-GH-14576.js

@@ -0,0 +1,47 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+/*
+ * Tests for sampler deadlock regression. 
+ * Issue https://github.com/joyent/node/issues/14576
+ */
+
+var assert = require('assert');
+var cp = require('child_process');
+
+var child = undefined;
+
+var deadlockTimer = setTimeout(function() {
+  if(child) {
+    process.kill(child.pid, 'SIGKILL');
+  }
+
+  assert(false, 'Node.js process hung');
+}, 10000);
+
+var testScript = "var i = 0; function r() { if(i++ > 2000) return; setTimeout(r, 1); }; r();";
+var child = cp.exec(process.execPath + ' --prof -e "' + testScript + '"', function(err, stdout, stderr) {
+  clearTimeout(deadlockTimer);
+  assert.ifError(err);
+
+  // no process hanging, test passed
+});
+