[ https://issues.apache.org/jira/browse/SOLR-15859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17633402#comment-17633402 ]
Ben Manes commented on SOLR-15859: ---------------------------------- > I figured that my synchronization additions wouldn't drastically alter > performance because Caffeine is probably already doing something similar > itself... I felt what I was adding to synchronization should be pretty fast > and not cause major issues. Caffeine does lock free reads on a cache hit, so reads easily scale to 100s of millions per second whereas writes throttle to ~50M/s. A global lock would throttle both to ~10M ops/s ([benchmarks|https://github.com/ben-manes/caffeine/wiki/Benchmarks#read-100-1]). The trick is that Caffeine appends into lossy ring buffers on a read to batch those events and uses a {{tryLock}} to replay then against the policy in a non-blocking fashion. This way it sidesteps the LRU problem of ever read is a write to global state by instead writing to a cheaper array, striped by thread id, in a best-effort fashion so that the metadata write is almost free and does not block progress. > Add handler to dump filter cache > -------------------------------- > > Key: SOLR-15859 > URL: https://issues.apache.org/jira/browse/SOLR-15859 > Project: Solr > Issue Type: Improvement > Reporter: Andy Lester > Assignee: Shawn Heisey > Priority: Major > Labels: FQ, cache, filtercache, metrics > Attachments: cacheinfo.patch, fix_92_startup.patch > > > It would be very helpful to be able to inspect the contents of the > filterCache. > I'd like to be able to query something like > {{/admin/caches?type=filter&nentries=1000&sort=numHits+DESC}} > nentries would be allowed to be -1 to get everything. > It would be nice to see these data items for each entry. I don't know which > are available, but I'm thinking blue sky here: > * cache key, exactly as stored > * Timestamp when the entry was inserted > * Whether the insertion of the entry evicted another entry, and if so which > one > * Timestamp of when this entry was last hit > * Number of hits on this entry forever > * Number of hits on this entry over some time period > * Number of documents matched by the filter > * Number of bytes of memory used by the filter > These are the sorts of questions I'd like to be able answer: > * "I just did a query that I expect will have added a cache entry. Did it?" > * "Are my queries hitting existing cache entries?" > * "How big should I set my filterCache size? Should I limit it by number of > entries or RAM usage?" > * "Which of my FQs are getting used the most? These are the ones I want in > my firstSearcher queries." (I currently determine this by processing my old > solr logs) > * "Which filters give me the most bang for the buck in terms of RAM usage?" > * "I have filter X and filter Y, but would it be beneficial if I made a > filter X AND Y?" > * "Which FQs are used more at certain times of the day? (Assuming I take > regular snapshots throughout the day)" > I imagine a response might look like: > {{{}} > {{ "responseHeader": {}} > {{ "status": 0,}} > {{ "QTime": 961}} > {{ },}} > {{ "response": {}} > {{ "numFound": 12104,}} > {{ "filterCacheKeys": {}} > {{ [}} > {{ "language:eng": {}} > {{ "inserted": "2021-12-04T07:34:16Z",}} > {{ "lastHit": "2021-12-04T18:17:43Z",}} > {{ "numHits": 15065,}} > {{ "numHitsInPastHour": 2319,}} > {{ "evictedKey": "agelevel:4 shippable:Y",}} > {{ "numRecordsMatchedByFilter": 24328753,}} > {{ "bytesUsed": 3041094}} > {{ }}} > {{ ],}} > {{ [}} > {{ "is_set:N": {}} > {{ ...}} > {{ }}} > {{ ],}} > {{ [}} > {{ "language:spa": {}} > {{ ...}} > {{ }}} > {{ ]}} > {{ }}} > {{}}} -- This message was sent by Atlassian Jira (v8.20.10#820010) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@solr.apache.org For additional commands, e-mail: issues-h...@solr.apache.org