On 01/15/2013 09:04 PM, Christopher Faylor wrote:
On Tue, Jan 15, 2013 at 05:16:57PM -0500, Tom Honermann wrote:
I noticed that some changes were checked in related to signal handling
and process termination recently, so I downloaded the most recent
snapshot (20130114) and tested again.  I was still able to produce
hanging processes (including hangs of strace.exe) by hitting ctrl-c in a
mintty window while Cygwin processes ran in an infinite loop inside of a
.bat file.  I was able to produce a hang ~1 out of 20 times.

How does one run a .bat file inside mintty which handles CTRL-C?  AFAIK,
a CTRL-C will just cause the .bat file to exit when run under bash.

Here is the test case:

1) Install the latest snapshot

2) Copy bash.exe, false.exe, and their dependent DLLs from a Cygwin install into the usr/bin directory of the snapshot. For me this consisted of:
  bash.exe
  cygintl-8.dll
  cygiconv-2.dll
  cygreadline7.dll
  cygncurses-10.dll
  cygncursesw-10.dll
  cyggcc_s-1.dll
  false.exe

3) Create 'test.bat' in the usr/bin directory of the snapshot with the following contents:

@echo off
setlocal

set PATH=%CD%;%PATH%

:loop
echo test...
bash -c false
if not errorlevel 1 (
    echo exiting...
    exit /B 1
)
goto loop

4) Launch mintty using an existing Cygwin installation. Naturally, this will run a shell from the existing Cygwin install.

5) Change directories to the usr/bin directory of the snapshot.

6) Start task manager or some other process monitoring tool and keep it running. Run ./test.bat from the Cygwin shell running within mintty and interrupt it with ctrl-c. Repeat until you see a new bash.exe or false.exe process persisting following the interrupt. You'll likely have multiple bash processes running. If you are able to reproduce, you should see one with a command line of 'bash -c false'. Alternatively, if your process monitoring tool shows the path to the executable, you'll be able to identify it as the one from the usr/bin directory of the snapshot.

I rather doubt that the use of a .bat file is necessary to reproduce this hang, but I haven't tried producing a test case that doesn't use a .bat file. This is a test case I was using when debugging the intermittent incorrect exit code issue.

Tom.


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