On 15 October 2013 03:15, Dimitar Zhekov <dimitar.zhe...@gmail.com> wrote:
> Hi, > > I'm looking how to fix this famous bug without too many changes, and > found something strange: tools.c runs it's command with spawn async, > but uses blocking I/O to read the data from stdout/stderr. > Given that it sets up io channels and callbacks when data is available I suspect that the writer thought they were using asynchronous i/o. ;) > > Any idea why is that? What comes to ming is blocking Geany until the > command finishes, to be sure that the current document still exists and > it's selection is unchanged, and thus can be safely replaced with the > command output. > This would be a correct reason to block Geany, but deliberately, not by accident. > > However, if we block reading stderr on Windows, and the command outputs > 4KB (or whatever is the limit) to stdout, that'll cause a deadlock, as > evident by the previous messages in this thread. Same if reading stdout > and the command produces a lot of stderr, though that's unlikely. > Its likely to do the same on Linux, but IIUC the limit is larger these days, 64k = 16 * PIPE_BUF. (The 16 is a #define in the kernal) > > I can emulate the (non-)blocking behaviour, but am not sure if this > flag currently has any effect under Windows, considering it's buggy > implementation of g_io_add_watch and g_io_channel_set_flags for > pipes (which are the problem to fix in the first place). > > Or possibly try the more complicated GIO g_input_stream_read_async() and friends and see if it works on windows. > If tools_execute_custom_command really wants to block Geany, the right > thing is to spawn the command, and then cycle reading stderr and > stdout asynchronously until the command completes, instead of adding > I/O watches to the message loop just to block it. > > The current loop that writes the selection to stdin seems capable of > causing a deadlock under Windows too, if the command generates 4KB > output and stops before the full selection is written, since we use > blocking I/O to write to stdin... > And not just on windows, if the selection is a whole file it can easily exceed the Linux limit of 64k. Basically the whole spawning thing needs to be looked at critically, especially those uses that do i/o to the child process. A working version of each permutation sync/async, reads/writes/both needs to be put in utils and all of Geany should then use that implementation and the callbacks use known good idioms. Cheers Lex > > -- > E-gards: Jimmy > _______________________________________________ > Devel mailing list > Devel@lists.geany.org > https://lists.geany.org/cgi-bin/mailman/listinfo/devel >
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