pá 7. 5. 2021 v 21:56 odesílatel David Rowley <dgrowle...@gmail.com> napsal:
> On Sat, 8 May 2021 at 07:18, Pavel Stehule <pavel.steh...@gmail.com> > wrote: > > yes, the slowdown is related to debug assertions > > With USE_ASSERT_CHECKING builds, I did add some code that verifies the > memory tracking is set correctly when evicting from the cache. This > code is pretty expensive as it loops over the entire cache to check > the memory accounting every time we evict something from the cache. > Originally, I had this code only run when some other constant was > defined, but I ended up changing it to compile that code in for all > assert enabled builds. > > I considered that it might be too expensive as you can see from the > comment in [1]. I just wanted to get a few machines other than my own > to verify that the memory accounting code was working as expected. > There have been no complaints of any Assert failures yet, so maybe > it's safe to consider either removing the code entirely or just having > it run when some other more specific to purpose constant is defined. > If we did the latter, then I'd have concerns that nothing would ever > run the code to check the memory accounting, that's why I ended up > changing it to run with USE_ASSERT_CHECKING builds. > I understand. I think this is too slow for generic assertions, because the overhead is about 50x. But I understand, so it may be necessary to have this code active some time. Regards Pavel > David > > [1] > https://github.com/postgres/postgres/blob/master/src/backend/executor/nodeResultCache.c#L305 >
