gc refcount related crash when loading web UI under Python 2.6.6 about locust

[cgbystrom]

That sounds really strange. We've run Locust fine for countless hours under different 2.6.x versions.

1. Are you using a vanilla CentOS 6.3 version?
2. Did you use the default Python interpreter that CentOS was shipped with or did you build it yourself?

Since I haven't experienced this myself I did quick google and for some this issue is caused by too aggressive compilation options when building the Python interpreter.

[Jahaja]

I was able to reproduce the problem using a minimal centos 6.3 installation on a VM. As well as using the python version that's shipped with it.

It seems to be related to gevent. Updating gevent to 1.0rc2 seems to solve the problem. So that should be a work-around for now.

[cgbystrom]

I was able reproduce it as well. @Jahaja's fix works!

Will close this issue as there is a short term workaround and it will be solved when gevent hits 1.0 (Locust will switch).
If you still have issues, please comment.

[daubman]

Would you please provide some more details on the fix, I have tried this and it does not appear to help - here's what I've done:

$ uname -a
Linux ip-10-46-247-69 2.6.32-71.29.1.el6.x86_64 #1 SMP Mon Jun 27 19:49:27 BST 2011 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/redhat-release
CentOS release 6.3 (Final)

$ which python
/usr/bin/python
$ python --version
Python 2.6.6

$ yum install c-ares-devel
$ yum install libev-devel
$ yum install zeromq-devel
$ pip install https://github.com/downloads/SiteSupport/gevent/gevent-1.0rc2.tar.gz
$ pip search gevent
gevent - Python network library that uses greenlet and libevent for easy and scalable concurrency
INSTALLED: 1.0rc2
LATEST: 0.13.8
...
$ pip install https://github.com/locustio/locust/archive/master.zip
$ pip install gevent-zeromq
$ pip install pyzmq
$ locust -f my_locust_file.py --master
[2013-01-08 16:07:53,945] INFO/locust.main: Starting web monitor on port 8089
[2013-01-08 16:07:53,947] ERROR/stderr: Traceback (most recent call last):
[2013-01-08 16:07:53,947] ERROR/stderr: File "/usr/bin/locust", line 9, in
[2013-01-08 16:07:53,948] ERROR/stderr:
[2013-01-08 16:07:53,948] ERROR/stderr: load_entry_point('locustio==0.6.1', 'console_scripts', 'locust')()
[2013-01-08 16:07:53,948] ERROR/stderr: File "/usr/lib/python2.6/site-packages/locust/main.py", line 363, in main
[2013-01-08 16:07:53,948] ERROR/stderr:
[2013-01-08 16:07:53,948] ERROR/stderr: runners.locust_runner = MasterLocustRunner(locust_classes, options.hatch_rate, options.num_clients, num_requests=options.num_requests, host=options.host, master_host=options.master_host)
[2013-01-08 16:07:53,948] ERROR/stderr: File "/usr/lib/python2.6/site-packages/locust/runners.py", line 241, in init
[2013-01-08 16:07:53,948] ERROR/stderr:
[2013-01-08 16:07:53,949] ERROR/stderr: self.greenlet.spawn(self.client_listener).link_exception()
[2013-01-08 16:07:53,949] ERROR/stderr: File "/usr/lib64/python2.6/site-packages/gevent/greenlet.py", line 370, in link_exception
[2013-01-08 16:07:53,949] ERROR/stderr:
[2013-01-08 16:07:53,949] ERROR/stderr: self.link(receiver=receiver, SpawnedLink=SpawnedLink)
[2013-01-08 16:07:53,949] ERROR/stderr: File "/usr/lib64/python2.6/site-packages/gevent/greenlet.py", line 355, in link
[2013-01-08 16:07:53,949] ERROR/stderr:
[2013-01-08 16:07:53,949] ERROR/stderr: self.rawlink(SpawnedLink(receiver))
[2013-01-08 16:07:53,950] ERROR/stderr: File "/usr/lib64/python2.6/site-packages/gevent/greenlet.py", line 23, in init
[2013-01-08 16:07:53,950] ERROR/stderr:
[2013-01-08 16:07:53,950] ERROR/stderr: raise TypeError("Expected callable: %r" % (callback, ))
[2013-01-08 16:07:53,950] ERROR/stderr: TypeError
[2013-01-08 16:07:53,950] ERROR/stderr: :
[2013-01-08 16:07:53,950] ERROR/stderr: Expected callable: None
[2013-01-08 16:07:53,950] ERROR/stderr:

Also, from this post, it appears locust's use of gevent is not compatible with 1.0rc2:
https://groups.google.com/forum/?fromgroups=#!topic/gevent/JHbtDU5HtL8

[heyman]

I've just pushed some changes which I think fixes the problems. Could you try to see if works and then I can push a new version to PyPI.

Thanks for reporting!

[jvenkataramanan]

Yes this change seems to fix all the issues. Thanks for getting to it so fast!

[heyman]

That's great to hear! The fix is now in a new 0.6.2 release on PyPI.