Bug 49164 – [NRWT] If the http lock fails we shouldn't do any locking

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Gabor Rapcsanyi]

If something go wrong with the locking, the test should keep going.
Now if it can't create the lock it waits indefinitely.

[Gabor Rapcsanyi]

Created attachment 73224 [details]
proposed patch

I put some error check into http_lock.py:
  - lock directory existence check
  - time limit for lock creation

[Csaba Osztrogonác]

Comment on attachment 73224 [details]
proposed patch

It is a good workaround to find why the Chromium Windows bot fails when we make http locking default.
Let's watch the bot!

[Csaba Osztrogonác]

Landed in http://trac.webkit.org/changeset/71525

[Csaba Osztrogonác]

We catched it:

2010-11-08 08:43:35,744 http_lock.py:125  DEBUG Lock does not created: (<type 'exceptions.OSError'>, OSError(17, 'File exists'), <traceback object at 0x026D7418>)
2010-11-08 08:43:35,744 http_lock.py:132  DEBUG Warning, http locking failed!
2010-11-08 08:43:35,744 dump_render_tree_thread.py:545  DEBUG Starting HTTP server ...

---

It means that _guard_lock_file (WebKit.lock) already exists, because 
it was probably left during previous tries of enabling this feature.

One of you Chromium guys, could you remove WebKit.lock file in tempfile.gettempdir() to make http locking work on Chromium-Win bots? 
- "Chromium Win Release (Tests)" bot on build.webkit.org
- "Webkit Win" bot on http://build.chromium.org/p/chromium.webkit/waterfall

But of course it isn't the perfect way to avoid this problem in the future.

---
in def _create_lock_file(self):
    sequential_guard_lock = os.open(self._guard_lock_file, os.O_CREAT | os.O_EXCL)
---

This kind of locking will always fail when a WebKit.lock is stucked for some reason. (e.g. script crashes before unlinking the lock file) I prefer a similar way as in httpd.pm, which always open the lock file and then try to grab the exclusive lock for it:

while (!(open(SEQUENTIAL_GUARD_LOCK, ">$exclusiveLockFile") && flock(SEQUENTIAL_GUARD_LOCK, LOCK_EX|LOCK_NB))) {}

[Tony Chang]

(In reply to comment #4)
> One of you Chromium guys, could you remove WebKit.lock file in tempfile.gettempdir() to make http locking work on Chromium-Win bots? 
> - "Chromium Win Release (Tests)" bot on build.webkit.org
> - "Webkit Win" bot on http://build.chromium.org/p/chromium.webkit/waterfall

I deleted the file on the WebKit Win bot on the chromium waterfall.  dglazkov can remove the file (I found it in c:\Documents and Settings\chrome-bot\Local Settings\Temp\) on Chrome Win Release (Tests).