[Geany-devel] win32_spawn hangs if child process writes more than 4kb to stdout

[Lex Trotman]

On 16 July 2011 07:46, Josh Pschorr <josh at pschorr.org> wrote:
> Hi,
> I ran into an issue using Geany on Windows where-in using either the build
> or compile
> commands to kick off a custom script caused Geany to hang for about a
> minute, after
> which it returned and the compiler log showed only a fraction of the output
> it should.
> After tracking this down, it seems that on Windows, a custom spawn function
> is used
> in build_spawn_cmd and rather than
> g_spawn_async_with_pipes, utils_spawn_sync
> which ends up calling win32_spawn.
> win32_spawn would set up pipes for stdout and stderr (using default buffer
> size),
> kick off the a child process, wait for it finish, and finally dump the
> stdout/stderr pipes
> to a temp file and then read that into memory. if the process didn't exit
> after a minute,
> it was forcefully killed.
> The problem seems to be that pipes are only 4kb buffered by default, so any
> process
> needing to write more than this would block while writing to stdout and
> Geany would
> kill it, as it wasn't reading the pipes until after the process exited.
> The attached patch fixes this such that the pipes are read and dumped to the
> temp
> file continuously as the child process runs.  Now the child process will be
> forcibly killed
> only if it doesn't write to one of its pipes for at least 30 seconds.
>
>
>
> Out of curiosity, why isn't g_spawn_async_with_pipes used on Windows?  It
> seems to
> work with some degree of success for the grep command (as used
> by search_find_in_files),
> albeit without completion status reporting.
>
> Regards,
> Josh Pschorr
>

For background see
http://lists.uvena.de/geany-devel/2009-April/000584.html and
associated messages.

Cheers
Lex

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