Just a heads up, with the patch mentioned above, we managed to backup a data of 3TB in 50 minutes with `solr.maxExpensiveTaskThreads=5` [1]
I would like to contribute to Solr, however, I'm unsure of the steps I should take if no one is available to take on this patch. 1. https://imgur.com/a/AAd0czU On Tue, 30 Jul 2024 at 16:53, Hakan Özler <ozler.ha...@gmail.com> wrote: > Hi!, > > We're experiencing performance issues in the recent Solr versions — 9.5.0 > and 9.6.1 — regarding backup and restore. In 9.2.1, we could take a backup > of 10TB data in just 1 and a half hours. Currently, as of 9.5.0, taking a > backup of the collection takes 7 hours! We're unable to make use of > disaster recovery effectively and reliably in Solr. Therefore, Solr 9.2.1 > still remains the most effective choice among the other 9.x versions for > our use. > > It seems that this is the ticket causing this issue: > 1. https://issues.apache.org/jira/browse/SOLR-16879 > > Interestingly, we never encountered a throttling problem during operations > when this was introduced to be solved based on this argument on 9.2.1. From > a devops perspective, we have some details and metrics on these tasks to > distinguish the difference between two versions. The overall IOPS was 150MB > on 9.6.1, while IOPS was 500MB on 9.2.1 during the same backup and restore > tasks. In the first image [1], the peak on the left represents a backup, in > contrast, in the 2nd image [2], the same backup operation in 9.5.0 uses > less resource. As you may spot, 9.5.0 seems to be using a fifth of the > resources of 9.2.1. > > Apart from that, monitoring some relevant metrics during the operations, I > had some difficulty interpreting the following metrics: > > "ADMIN./admin/cores.threadPool.parallelCoreExpensiveAdminExecutor.pool.core": > 0, > "ADMIN./admin/cores.threadPool.parallelCoreExpensiveAdminExecutor.pool.max": > 5, > "ADMIN./admin/cores.threadPool.parallelCoreExpensiveAdminExecutor.pool.size": > 1, > "ADMIN./admin/cores.threadPool.parallelCoreExpensiveAdminExecutor.running": > 1, > > The pool size was 1 although the pool max size is 5. Shouldn't the pool > size be 5, instead? However, there is always one task running on a single > node, not 5 concurrently, if I'm not mistaken. > > I was also wondering if the max thread size, which is currently 5 in 9.4+, > could be configurable with either an environment variable or Java > parameter? The part that needs to be changed seems to be in > CoreAdminHandler.java on line 446 [3] I've made a small adjustment to add a > Solr parameter called `solr.maxExpensiveTaskThreads` for those who want to > set a different thread size for expensive tasks. The number given in this > parameter must meet the criteria of ThreadPoolExecutor, otherwise > IllegalArgumentException will occur. I've generated a patch [4] and I would > love to see if someone from the Solr committers would take on this and > apply for the upcoming release. Do you think our observation is accurate > and would this patch be feasible to implement? > > Thanks! > Hakan > > 1. https://i.imgur.com/aSrs8OM.png > 2. https://i.imgur.com/Yr6hBM8.png > 3. > https://github.com/apache/solr/commit/82a847f0f9af18d6eceee18743d636db7a879f3e#diff-5bc3d44ca8b189f44fe9e6f75af8a5510463bdba79ff72a7d0ed190973a32533L446 > 4. https://gist.github.com/ozlerhakan/e4d11bddae6a2f89d2c212c220f4c965 > >
