Re: Perl backtick childprocs hang after completion

["Larry Hall (RFK Partners, Inc)" <lhall at rfk dot com>]

At 07:57 PM 1/18/2001, David M. Karr wrote:
>I'm seeing a weird symptom with the child process belonging to a
>backtick command in Cygwin Perl.
>
>I wrote a little Perl script that just takes a command line to run,
>captures the output, and replaces "\\" with "/".  The vast majority of
>the time, it seems to work fine.
>
>However, either because of the command I'm wrapping ("cleartool lsvt
>-a dirname"), or the directory I'm running it in, or something about
>the output it produces, it will sometimes just "hang" after calling
>the child process.
>
>I accidently discovered that if I use Task Manager to manually kill
>the child process, then the backtick finishes, and the captured output
>is exactly what it's supposed to be.  So it appears that all the
>output was produced, but it somehow hung trying to end the child
>process.
>
>When I run this on a set of directories, it always hangs on the same
>ones.  I looked at the output which is produced by each directory in
>the list I'm trying, and the ones that are failing represent the ones
>with the most number of lines of output, although they only range from
>36-197 lines.  However, there is one other that produces 36 lines of
>output, and that one does NOT fail.
>
>I tried storing the lines of output that "hang" into a file and
>changing the backticked command to "cat thefile", and doesn't hang.
>
>I'm quite confused.  What could be going on here?



Running strace on the Perl process might shed some light on your problem.



Larry Hall                              lhall@rfk.com
RFK Partners, Inc.                      http://www.rfk.com
118 Washington Street                   (508) 893-9779 - RFK Office
Holliston, MA 01746                     (508) 893-9889 - FAX



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