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Threading hesitates in 2005Hi everyone,
We have an application originally written in VS2003 that spawned a number of threads (10-20 or so) for initialization of the application. Every thread performs the exact same task in a few hundered milliseconds. In VS2003 the app worked wonderfully. Now we have upgraded the application to VS2005 using the exact same code. After a number of threads kick off, the app suddenly pauses for anywhere between a few seconds to a few minutes, apparently as a result of creating the next thread. After the app pauses, the remaining threads are created and run as if nothing happened. Did something change in Visual Studio 2005 that would cause this behavior? Thanks, Bob Bob L. <nospam.info2@libertyfamily.net> wrote:
> We have an application originally written in VS2003 that spawned a number of Could you post a short but complete program which demonstrates the> threads (10-20 or so) for initialization of the application. Every thread > performs the exact same task in a few hundered milliseconds. In VS2003 the > app worked wonderfully. > > Now we have upgraded the application to VS2005 using the exact same code. > After a number of threads kick off, the app suddenly pauses for anywhere > between a few seconds to a few minutes, apparently as a result of creating > the next thread. After the app pauses, the remaining threads are created and > run as if nothing happened. > > Did something change in Visual Studio 2005 that would cause this behavior? problem? See http://www.pobox.com/~skeet/csharp/complete.html for details of what I mean by that. -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too Jon,
I am still working on putting together a program while balancing my other tasks. In the mean time, I have a guess that this has something to do with communicating from the threads to the user interface (I apologize for leaving this out before). I know something changed in VS2005, because when we upgraded we had to include more UI code inside our Invoke calls to avoid UI threading exceptions (evidently the requirements are tighter in 2005). Now if I comment out the calls to the UI, the app starts fine. Even though the calls to the UI themselves don't hang the app, it almost appears as if each call to the UI accumulates a delay that appears when starting a future thread. Very strange. In the mean time, I will continue to work on this demo app and try to find the key to reproduce the problem. - Bob Show quote "Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message news:MPG.1e3bf476c34283b498cd38@msnews.microsoft.com... > Bob L. <nospam.info2@libertyfamily.net> wrote: > > We have an application originally written in VS2003 that spawned a number of > > threads (10-20 or so) for initialization of the application. Every thread > > performs the exact same task in a few hundered milliseconds. In VS2003 the > > app worked wonderfully. > > > > Now we have upgraded the application to VS2005 using the exact same code. > > After a number of threads kick off, the app suddenly pauses for anywhere > > between a few seconds to a few minutes, apparently as a result of creating > > the next thread. After the app pauses, the remaining threads are created and > > run as if nothing happened. > > > > Did something change in Visual Studio 2005 that would cause this behavior? > > Could you post a short but complete program which demonstrates the > problem? > > See http://www.pobox.com/~skeet/csharp/complete.html for details of > what I mean by that. > > -- > Jon Skeet - <sk***@pobox.com> > http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet > If replying to the group, please do not mail me too Well, I found the solution, but I still don't know the problem. It doesn't
appear to be UI related after all. Before all the initialization threads kick off, there is one task that executes on a single thread (there can be more than one, but in my test case there is only one). If the first thread has a priority set to BelowNormal, the initialization threads stop (hesitate) part way through startup. If the priority of the first thread is Normal, everything works great. Any idea why this is a problem in 2005, but not in 2003? Thanks, Bob P.S. I still don't have a test app yet - I'll see what I can come up with. Show quote "Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message news:MPG.1e3bf476c34283b498cd38@msnews.microsoft.com... > Bob L. <nospam.info2@libertyfamily.net> wrote: > > We have an application originally written in VS2003 that spawned a number of > > threads (10-20 or so) for initialization of the application. Every thread > > performs the exact same task in a few hundered milliseconds. In VS2003 the > > app worked wonderfully. > > > > Now we have upgraded the application to VS2005 using the exact same code. > > After a number of threads kick off, the app suddenly pauses for anywhere > > between a few seconds to a few minutes, apparently as a result of creating > > the next thread. After the app pauses, the remaining threads are created and > > run as if nothing happened. > > > > Did something change in Visual Studio 2005 that would cause this behavior? > > Could you post a short but complete program which demonstrates the > problem? > > See http://www.pobox.com/~skeet/csharp/complete.html for details of > what I mean by that. > > -- > Jon Skeet - <sk***@pobox.com> > http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet > If replying to the group, please do not mail me too Bob L. <nospam.info1@libertyfamily.net> wrote:
> Well, I found the solution, but I still don't know the problem. It doesn't It's possible that the priority of the JIT has changed between .NET 1.1 > appear to be UI related after all. > > Before all the initialization threads kick off, there is one task that > executes on a single thread (there can be more than one, but in my test case > there is only one). If the first thread has a priority set to BelowNormal, > the initialization threads stop (hesitate) part way through startup. If the > priority of the first thread is Normal, everything works great. Any idea why > this is a problem in 2005, but not in 2003? > > P.S. I still don't have a test app yet - I'll see what I can come up with. and .NET 2.0, so that while your thread used to have priority over the JIT, it no longer does unless you've got a priority set to Normal. Just a guess though... -- Jon Skeet - <sk***@pobox.com> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet If replying to the group, please do not mail me too Sounds like there may be a bug in .NET 1.1's thread priority settings. If a
native Win32 App thread is at a low priority, other threads will run before it. A perfect example of this was the Seti@Home Command Line Client 3.08 for Windows. It ran at Priority 4. Unfortunately, offline folders syncronization in Windows XP and Outlook XP runs at either Priority 2 or 3. Effectively the Seti client would freeze the offline folders features (and in the case of Windows XP, the entire shell because this is a "critical path" function in the shell). The SETI GUI client for windows properly set itself to priority 1 in the system and didn't interfere with offline folders. Eventually all runnable threads will execute because for every few timeslices a thread doesn't get to run, the thread priority gets boosted until it is has the highest priority of runnable threads. This behavior exhibits itself as pauses and jerkyness in the execution of the thread. As for "normal priority" in a thread. The default thread priority is 6. Windows automatically boosts this to 7 for the thread that currently has the keyboard/mouse focus to make user interfaces more responsive. This boost is also given to the initial thread of an application that is launched with the SW_NORMAL window option. In your code, check for any Thread.Priority statements in your initialization code and comment them out. Mike Ober Show quote "Bob L." <nospam.info1@libertyfamily.net> wrote in message news:OKoyWZRIGHA.1836@TK2MSFTNGP11.phx.gbl... > Well, I found the solution, but I still don't know the problem. It doesn't > appear to be UI related after all. > > Before all the initialization threads kick off, there is one task that > executes on a single thread (there can be more than one, but in my test case > there is only one). If the first thread has a priority set to BelowNormal, > the initialization threads stop (hesitate) part way through startup. If the > priority of the first thread is Normal, everything works great. Any idea why > this is a problem in 2005, but not in 2003? > > Thanks, > Bob > > P.S. I still don't have a test app yet - I'll see what I can come up with. > > "Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message > news:MPG.1e3bf476c34283b498cd38@msnews.microsoft.com... > > Bob L. <nospam.info2@libertyfamily.net> wrote: > > > We have an application originally written in VS2003 that spawned a > number of > > > threads (10-20 or so) for initialization of the application. Every > thread > > > performs the exact same task in a few hundered milliseconds. In VS2003 > the > > > app worked wonderfully. > > > > > > Now we have upgraded the application to VS2005 using the exact same > code. > > > After a number of threads kick off, the app suddenly pauses for anywhere > > > between a few seconds to a few minutes, apparently as a result of > creating > > > the next thread. After the app pauses, the remaining threads are created > and > > > run as if nothing happened. > > > > > > Did something change in Visual Studio 2005 that would cause this > behavior? > > > > Could you post a short but complete program which demonstrates the > > problem? > > > > See http://www.pobox.com/~skeet/csharp/complete.html for details of > > what I mean by that. > > > > -- > > Jon Skeet - <sk***@pobox.com> > > http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet > > If replying to the group, please do not mail me too > >  |
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