Re: git diff looping?

> On Mon, Jun 15, 2009 at 06:37:21PM -0700, John Bito wrote:
>
>> Running Git 1.6.1 on Solaris 10, git diff seems to go into a loop -
>> consuming CPU and producing no output after a little bit.  While the
>> repository isn't small, it's not huge (it's
>> http://repo.or.cz/w/egit.git). I've tried the following:
>
> I can reproduce the problem on Solaris 8 using git v1.6.3. It seems to
> be caused by a horribly slow system regex implementation; it really
> chokes on the regex we use to find the "funcname" line for java files. I
> tried running "git diff v0.4.0" and it still hadn't finished after 90
> seconds. Then I did:
>
>  git config diff.java.xfuncname foo ;# some garbage regex
>  git diff v0.4.0
>
> and it completed in about 2.5 seconds.
>
> Can you try that and see if it works around the problem for you?
>
> If anybody wants to look further into the problem, I think it is
> specifically triggered by this file (and the built-in xfuncname for java
> files):
>
>  $ git clone git://repo.or.cz/egit.git
>  $ git diff v0.4.0 -- \
>    org.spearce.egit.core.test/src/org/spearce/egit/core/op/T0001_ConnectProviderOperationTest.java
>
> which isn't even all that big a file, but it is either causing some
> horrible algorithmic behavior in the regex library, or is outright
> sending it into an infinite loop.
>
> I tried building against the code in compat/regex; it completes in a
> reasonable amount of time, though it is still noticeably slow. With
> system regex, the diff given above doesn't complete in less than 90
> seconds (at which I get bored and kill it). With compat/regex, it
> completes in about 2.2 seconds. Disabling the xfuncname, it completes in
> 0.14 seconds.
>
> So I think it is a viable solution to recommend building against
> compat/regex on Solaris, but I think there is still room for improvement
> in what we ship in compat/.
>
> -Peff
>