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Delays With Pipes In Cygwin 1.3.18


I just upgraded to Cygwin 1.3.18:

% uname -a
CYGWIN_NT-5.0 CLEMENS 1.3.18(0.69/3/2) 2002-12-25 15:37 i686 unknown

Immediately after doing so I began noticing a heretofore unseen problem.

Every command I run that involves a pipe produces a large delay, though they all eventually complete normally. This is true when I use the pipeline explicitly or in a shell procedure or alias as well as in commands such as "man" that use pipes internally.

Using "nice" to start a shell with elevated priority (including going all the way to "nice --20" which produces a process listed as "High" priority in the Task Manager) does not alter this symptom. As expected, the elevated scheduling priority is inherited by the shell's children, but the delay remains.

I run the SETI@home client in always-on mode and that program is shown as having the lowest priority in the Windows Task Manager (by right-clicking on the "SETI@home.exe" line in the "Process" tab and opening the "Set Priority" sub-menu). BASH has "Normal" priority.

On a hunch, I stopped the SETI@home process and then pipelines complete with their usual alacrity even when started at the normal priority.

Nothing like this ever happened in the past, so I imagine this symptom is somehow related to the Cygwin changes that were designed to give better pipe performance.

I've attached "cygcheck -s -v" output.

I'd be happy to run other tests or supply other diagnostic information if anyone would like me to.

Randall Schulz

Attachment: cygcheck-slowpipe-out
Description: Binary data

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