[Mapguide-trac] [mapguide-trac] #2348: Crash in MapGuide Web Extensions upon web server shutdown

[MapGuide Open Source]

#2348: Crash in MapGuide Web Extensions upon web server shutdown
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   Reporter:  ydie22   |       Owner:             
       Type:  defect   |      Status:  new        
   Priority:  medium   |   Milestone:             
  Component:  Web API  |     Version:  2.5.0      
   Severity:  minor    |    Keywords:  ISAPI crash
External_id:           |  
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 This issue refers to a post made in the mapguide-internals and mapguide-
 users mailing lists on August, 22nd.

 We are currently experiencing a crash (almost systematic) of our web
 server process running the web extensions when shutting it down.

 The crash itself is an access violation. After some analysis, we think it
 could be due to an incomplete cleanup of allocated resources in
 MgUninitializeWebTierInternal(). Indeed, the connection pool is closed in
 that function, and right after that the ACE library is shutdown. But
 unfortunately, the SiteManager is not stopped, more precisely the
 background thread that regularly pings the server(s). As there is a call
 to sleep(1) in a loop in that thread (which keeps running during
 shutdown), what happens is that by the time the sleep(1) call returns, the
 operating system has already unloaded the DLL that hosts the code of the
 SiteManager
 (MgMapGuideCommon.dll), as the process is stopping. Therefore, as the code
 to execute after sleep(1) is no longer present in memory, that causes an
 access violation. It should probably be wise to stop the site manager
 background thread before allowing the web server to proceed with unloading
 the ISAPI extension and shutting down the process. By the way, the boolean
 flag m_bCheckServersThreadDone is not marked as volatile, couldn't that be
 an issue?

 Our environment(s):
 MapGuide 2.5.0
 Windows 7 (32-bit) or 8 (64-bit)
 IIS Express 8.0

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Ticket URL: <http://trac.osgeo.org/mapguide/ticket/2348>
MapGuide Open Source <http://mapguide.osgeo.org/>
MapGuide Open Source Internals