Thanks Nick, I'll take a look at that. I did add async-profiler to our image[1] but haven't had a chance to test it yet. Do you remember if you had to run the container with extra privileges?
I just opened this issue before I saw your mail as it turns out that not all args are exposed after all :) https://issues.apache.org/jira/browse/HBASE-28242 (ideas welcome in this ticket) I'll continue this journey and will report back with any issues and will see if I can improve anything [1] <https://github.com/stackabletech/docker-images/commit/ba957b37c8d4c679b918f3815e28d974b0bd008d> On Wed, Dec 6, 2023 at 9:06 AM Nick Dimiduk <ndimi...@apache.org> wrote: > > For what it’s worth, we deployed async-profiler into the regionserver > container image and it all worked as expected. But it’s not a sidecar > container, it’s on the same image as the region server. > > If you can get the async profiler into your container image, installed > where the RS can find it (as described in the online book; double-check you > have a version of AP that’s compatible with your version of the profiler > servlet), you should be able to use the profiling http endpoint on the RS. > It’ll run async-profiler with the arguments you specify (read the servlet > code, all args are exposed). You can then download the flamegraph via HTTP > as well … > > Well, most of the time. I have run into issues where the file wasn’t served > correctly and I had to download it from the region server file system > (annoying to do from a container). There’s probably a closed Jira where I > scratch my head in public. > > On Wed, 6 Dec 2023 at 08:15, Lars Francke <lars.fran...@gmail.com> wrote: > > > > > Also, are you sure you couldn't use async-profiler? We use this all the > > > > time in our very latency-sensitive production. It has no noticeable > > > > overhead in my experience and doesn't need any special dependencies. > > > > > > I have to admit, I have never used async-profiler. Shame on me. > > > That is a fabulous hint and I'll read up on it immediately. > > > > I now did read up on it, tried it locally, stumbled over > > https://issues.apache.org/jira/browse/HBASE-25685 and the fact that > > 2.4 fails weirdly using Java 21 only to find out (I should have read > > the whole docs earlier) that it's hard to run async-profiler in a > > container. > > For us, this is all running on Kubernetes, so we'll test that today. > > > > Testing i tlocally it looked very promising. > > > > > > > > > > > > > > > > > > On Tue, Dec 5, 2023 at 3:46 PM Lars Francke <lars.fran...@gmail.com> > > wrote: > > > > > > > > > Hi, > > > > > > > > > > I am debugging an issue where we see some Get requests taking 2-5s. > > > > > We do see "responseTooSlow" etc. and this is in an environment where > > I > > > > > cannot run a Profiler but I _can_ run modified code. > > > > > > > > > > So what I did was I added a stupid "MethodTimer"[1] which records how > > > > > long certain operations take at various points in the code (e.g. > > [2]). > > > > > I've been doing this a few rounds and have now arrived at the > > StoreScanner. > > > > > > > > > > I'm wondering if anyone has better ideas on how to diagnose this? > > > > > I am a HBase committer but I haven't been able to keep up with the > > > > > changes in the last 5-6 years so I'm not too familiar with the inner > > > > > workings anymore and would appreciate a hint. > > > > > > > > > > I suspect it is slowness related to storage access. > > > > > I was not able to find any logs or tweaks to log "slow storage" > > > > > access, does such a thing exist? > > > > > And something else that'd help me: Can anyone point me (if it exists) > > > > > at the (vicinity of the) code that actually reads from HDFS at the > > > > > end? There are so many layers. > > > > > > > > > > Thank you! > > > > > > > > > > Cheers, > > > > > Lars > > > > > > > > > > > > > > > [1] < > > > > > > > https://github.com/stackabletech/docker-images/blob/8349f29f8aded8a01a8d1dbf7a90776ede1764ca/hbase/stackable/patches/2.4.12/005-STACKABLE-profiling-2.4.12.patch#L150C5-L150C5 > > > > > > > > > > > [2] < > > > > > > > https://github.com/stackabletech/docker-images/blob/8349f29f8aded8a01a8d1dbf7a90776ede1764ca/hbase/stackable/patches/2.4.12/005-STACKABLE-profiling-2.4.12.patch#L289-L297 > > > > > > > > > > > > >
