[Qt-interest] Problems running QProcess under linux

[Thiago Macieira]

On Monday, 26 de September de 2011 13:37:19 Bill Crocker wrote:
> Scott Aron Bloom wrote:
> > Thanks.. the problem here is the crash takes 3-4 hours of running to
> > crash..  and has yet to be reproduced when run with the same command
> > line arguments from the CLI only...  hence my thoughts that it might be
> > a QProcess settings issue...
> 
> Create a small program which dumps all resource
> limits using getrlimit. Run this from a QProcess
> and see if the limits differ from a command line run.
> 
> You can also dump its list of env vars and see if there
> are any differences there.

Usually, the only difference between running from the command line and using 
QProcess is stdin, stdout and stderr. From the command-line, they are 
connected to a terminal; from QProcess, they are connected to a pipe.

By default, libc uses line-buffering with stdout when connected to a terminal, 
but full buffering when it's a file or pipe,

Also, reading from a terminal respects terminal settings (canonical mode, for 
example), whereas reading from a file or pipe is just that: reading.

It might be that the child process attempts to read a chunk of data expecting 
to get at most one line, but it eventually gets more than that and then falls 
out of sync.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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