Non-Cygwin slaves inside tmux

[David Macek <david.macek.0@gmail.com>]

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Hi.

My testcase: run mintty-bash, run tmux inside and run netsh inside. Try to type.

Result: horrible lags

Expected result: it's possible to type normally

I tried multiple Cygwin snapshots from the last 5 months, hoping that it could be a regression (therefore easily fixable), but all of them exhibit the same issue.

A quick Google search didn't show any similar errors, so I'm reporting here in hope someone will be able to say "yeah, that's easy, let me fix that". :)

Assuming I understand correctly the roles here -- bash does fork+exec(netsh) and Cygwin emulates that by creating a bash subprocess which creates a netsh subprocess; the bash process that is spawned to execute the native executable is creating threads and named pipes like crazy. Every few seconds a new pipe and thread pop up. All the old threads seem to be stuck in:

 #0 0x00007ffad7f3120a in ntdll!ZwWaitForSingleObject () from /cygdrive/c/Windows/SYSTEM32/ntdll.dll
 #1 0x00007ffad53b1118 in WaitForSingleObjectEx () from /cygdrive/c/Windows/system32/KERNELBASE.dll
 #2 0x0000000180134cfb in muto::acquire (this=0x639363438, ms=ms@entry=4294967295) at /usr/src/debug/cygwin-2.0.2-1/winsup/cygwin/sync.cc:87
 #3 0x00000001800f9ed9 in lock_process (exiting=false, this=) at /usr/src/debug/cygwin-2.0.2-1/winsup/cygwin/sync.h:53
 #4 commune_process (arg=0x6e7cb90) at /usr/src/debug/cygwin-2.0.2-1/winsup/cygwin/pinfo.cc:542
... several other frames which are related to Cygwin threads, I assume ...

strace shows tmux getting these:

seterrno_from_win_error: /usr/src/ports/cygwin/cygwin-2.0.2-1.x86_64/src/newlib-cygwin/winsup/cygwin/pinfo.cc:737 windows error 995

-- 
David Macek


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