pretxnchangegroup hook fails because it can't acquire lock

[Simon King]

On Tue, Nov 5, 2013 at 7:50 PM, Mick Jordan <mick.jordan at oracle.com> wrote:
> On 11/5/13 3:41 AM, Simon King wrote:
>>
>> [hooks] pretxnchangegroup.push =
>> python:/path/to/hook/script.py:pushwhilelocked
>
>
>> Hope that helps, Simon
>
> I have this working now, just one small problem that someone might know the
> answer to, which is that the hgweb script is evidently returning a bad
> header. It's nice that all the python logging shows up now in the server
> error_log Here are the salient lines:
>
> [Tue Nov 05 11:31:25 2013] [error] [client ...] abort:
> pretxnchangegroup.run_gate hook failed
> [Tue Nov 05 11:31:25 2013] [error] [client ...] malformed header from
> script. Bad header=listing keys for "bookmarks": hgweb.cgi
>
>

At a guess, your hook is producing some output on stdout. Since you
are using CGI, stdout from the script becomes part of the HTTP
response.

So you need to prevent your hook from outputting to stdout. If it were
an out-of-process hook, you could do this using standard shell
redirection operators, but for an in-process hook you'll have to do
something different. Completely untested, but you might be able to do
something like this:

import sys

def myhook(ui, repo, **kwargs):
    oldstdout = sys.stdout
    try:
        sys.stdout = sys.stderr
        do_stuff()
    finally:
        sys.stdout = oldstdout


If you have the option, it might be better to use WSGI rather than CGI
to host hgweb. The performance should be better, and it wouldn't have
problems like this.

Simon