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.NET Forum / .NET Framework / New Users / June 2007Release is slower than debug... What's happening?
Hi, I have a windows service that only loads a CSV file and import it's data using SqlBulkCopy in a newly created Sql Server 2005 table using 25000 rows batches. If I build the service in debug mode and run it, I get descent performances. If I build it in release mode, I would expect it to at least stay as fast and maybe be faster, but I actually lose performance. I lose about 10% performance. How can this happen? Here's what could be involved : - SqlBulkCopy Class a IDataReader implementation as a source which performance has been verified. - <SqlDbTypes>.Parse(...) - Array indexing - Boxing and Unboxing of objects - Generic classes (List, Dictionary, Hashtable) search by key Thanks ThunderMusic oups - SqlBulkCopy Class a IDataReader implementation as a source which performance has been verified. should read - SqlBulkCopy Class using a IDataReader implementation as a source which performance has been verified. > Hi, > I have a windows service that only loads a CSV file and import it's data [quoted text clipped - 19 lines] > > ThunderMusic > Hi, > I have a windows service that only loads a CSV file and import it's data [quoted text clipped - 7 lines] > > How can this happen? Are you measuring first run performance, or steady state? The first run requires that the JIT compiler be run, and in release mode the JIT has to look for optimizations, hence taking longer. After the code is compiled, however, the incremental cost of rerunning it is usually greatly reduced by the optimizations. > Here's what could be involved : > - SqlBulkCopy Class a IDataReader implementation as a source which [quoted text clipped - 7 lines] > > ThunderMusic Even after many runs, it's still slower. >> Hi, >> I have a windows service that only loads a CSV file and import it's data [quoted text clipped - 26 lines] >> >> ThunderMusic ThunderMusic, This simply "does not compute". Are you actually installing this windows service after it has been built in a debug build configuration? And you are comparing the performance against a different Windows Service installation that was done with a release build? What I'd do (unless you want to get into some heavy-duty profiling) is use the Stopwatch class to take some start / finish timings around critical operations that occur when your service runs, and write the results as appended lines to a text file. Examining this, if you have instrumented it properly, should give more insight. Peter  SignatureSite: http://www.eggheadcafe.com UnBlog: http://petesbloggerama.blogspot.com Short urls & more: http://ittyurl.net > Hi, > I have a windows service that only loads a CSV file and import it's data [quoted text clipped - 19 lines] > > ThunderMusic On Jun 1, 10:33 pm, Peter Bromberg [C# MVP] <pbromb...@yahoo.yabbadabbadoo.com> wrote: > ThunderMusic, > This simply "does not compute". Are you actually installing this windows [quoted text clipped - 41 lines] > > - Show quoted text - I was using same kind of functionality, but in the reverse way, loading data from SQL to CRM Server and then to MSMQ. Again from queue to a CSV file. The performance is considerably better when I built the windows service in release mode. I've found it out using the aforementioned Stopwatch class. I'd venture to suggest the same. Hi, Thanks for the answers... 1) Yes, it's the same service I'm testing, in debug, then in release (or in release then in debug, no importance, I get the same results) and always on the same computer. 2) The thing is, We are already logging when the application reach an important point (with Timestamps). So using Stopwatch here will only add overhead to the process. Actually, we are taking a 4000000 rows CSV and copy it to a SQL Table by taking care the datatypes are good. So we optimized our process and managed to get a good performance (by replacing most of the generics by native arrays, using temporary variables instead of always getting the current value from the file reader, et al.) maybe we optimized "too much" and the JIT cannot find a way to optimize intelligently... Would it be possible? Thanks ThunderMusic > On Jun 1, 10:33 pm, Peter Bromberg [C# MVP] > <pbromb...@yahoo.yabbadabbadoo.com> wrote: [quoted text clipped - 56 lines] > windows service in release mode. I've found it out using the > aforementioned Stopwatch class. I'd venture to suggest the same. > If I build the service in debug mode and run it, I get descent performances. > If I build it in release mode, I would expect it to at least stay as fast > and maybe be faster, but I actually lose performance. I lose about 10% > performance. > > How can this happen? A stab in the dark ... Do you handle many exceptions? My experience is that executing a 'try' gives no noticeable performance hit, but executing a 'catch' is very noticeable. So... maybe the non-catch part of your code runs slower in debug (as intuition dictates), and maybe the catch parts of your code run much slower in release (not sure why, perhaps there is more to untangle). As I said, a stab in the dark. > > How can this happen? > [quoted text clipped - 4 lines] > code run much slower in release (not sure why, perhaps there is more to > untangle). As I said, a stab in the dark. Catching an exception *in the debugger* takes a vast amount of time. Catching an exception in a release build, not running in the debugger, takes relatively little time. Unless you're throwing and catching thousands and thousands of exceptions, there shouldn't be any significant performance hit. SignatureJon Skeet - <skeet@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 No, I'm not throwing many exceptions. Actually, with the test we ran, none were thrown. so it must be in the non-catch part... ;) We still experience the problem independantly from being executed after a reboot or after running a while. We tried to measure with StopWatch, but nothing relevant came out of this because when run in a close loop, StopWatch tend to add overhead and it almost doubled our processing time. (in the file we are testing, we do a 4000000 iteration 'for' (rows, records) with an inner 13 iteration 'for' (columns, fields). So if we try to measure the total time doing parse and total time for writing in the array to send to bulk copy and the total time of anything, the StopWatch make make it go awry Would you have any other ideas so we can find what is going on? Thanks ThunderMusic >> > How can this happen? >> [quoted text clipped - 13 lines] > thousands and thousands of exceptions, there shouldn't be any > significant performance hit. > No, I'm not throwing many exceptions. Actually, with the test we ran, none > were thrown. so it must be in the non-catch part... ;) [quoted text clipped - 14 lines] > > ThunderMusic I don't get is, when using StopWatch doubles the processing time, it looks like you have your StopWatch calls at the wrong places, so I'm currious where you inserted the StopWatch calls, my guess is for each iteration, which is wrong when each iteration executes only a few statements. Mind to post some code? Also, did you compare the GC counters like Time Spent in GC and the number of Collections done for each generational heap when running both release and debug versions? Willy. >> No, I'm not throwing many exceptions. Actually, with the test we ran, >> none were thrown. so it must be in the non-catch part... ;) [quoted text clipped - 25 lines] > > Willy. For the StopWatch, we tried to nail down a section of the code where the processing is slower in release, but because of the structure of the code, we cannot place it elsewhere than inside a loop because all the work is done in a loop. So it's really hard to know exactly where we must look. I cannot post code because it would be a violation of my contract because I can't just simplify the code mainly because the problem could be anywhere in it. We didn't look for the GC counters... I'll look into that and come back with the results. Thanks ThunderMusic Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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