Add step to kill stale symbolizer processes before building

[rnk]

Summary

This comes up from time to time and we have to reboot the builder.

[eugenis]

LGTM

[eugenis]

Do you plan to land this change?
The bot has been failing for several days now due to the stale llvm-symbolizer problem.

[gkistanova]

LGTM.

Thanks

Galina

[rnk]

In D17785#372631, @eugenis wrote:

Do you plan to land this change?
The bot has been failing for several days now due to the stale llvm-symbolizer problem.

I rebooted it and now it is failing for different reasons:

Unexpected Passing Tests (1):

AddressSanitizer-i386-windows :: TestCases/printf-4.c

When Galina restarts the master we shouldn't have this problem anymore.

zorg/buildbot/builders/SanitizerBuilderWindows.py

def getSanitizerWindowsBuildFactory(
             config='Release',
             target_arch='x86',
 
             extra_cmake_args=[]):
 
     ############# PREPARING
     f = buildbot.process.factory.BuildFactory()
 
+    # Kill any stale symbolizer processes for the last run. If there are any
+    # stale processes, the build will fail during linking. This can happen to
+    # any process, but it is most likely to happen to llvm-symbolizer if its
+    # pipe isn't closed.
+    f.addStep(ShellCommand(name='taskkill',
+                           description='kill stale processes',
+                           command=['taskkill', '/f', '/im', 'llvm-symbolizer'],
+                           haltOnFailure=False))
+
     # Determine Slave Environment and Set MSVC environment.
     f.addStep(SetProperty(
         command=getVisualStudioEnvironment(vs, target_arch),
         extract_fn=extractSlaveEnvironment))
 
     f = getSource(f,'llvm')
 
     # Global configurations