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Aleksey Yeschenko commented on CASSANDRA-7507: ---------------------------------------------- The Python part should go into our CI system, probably - I don't want to complicate our build script further. +1 to the Java part, with some (subjective) nits: - I'd rename JVMStabilityInspector#inspectThrowable() to OOMInspector#maybeExit(), or something more obvious, like that. I get that the intent is to make it future-proof, but I don't see any other exceptions that we would consider unrecoverable, TBH. When and if that happens, we can generalize. - For the same reason, for now we should remove the isUnstable vairable and just do if (t instanceof OutOfMemoryError), + make the logged message mention OOM, and not be generic, until and unless we add another exception to the list of unrecoverables - should probably use logger.fatal() instead of logger.error() > OOM creates unreliable state - die instantly better > --------------------------------------------------- > > Key: CASSANDRA-7507 > URL: https://issues.apache.org/jira/browse/CASSANDRA-7507 > Project: Cassandra > Issue Type: New Feature > Reporter: Karl Mueller > Assignee: Joshua McKenzie > Priority: Minor > Fix For: 2.1.1 > > Attachments: 7507_v1.txt, 7507_v2.txt, 7507_v3_build.txt, > 7507_v3_java.txt, exceptionHandlingResults.txt, findSwallowedExceptions.py > > > I had a cassandra node run OOM. My heap had enough headroom, there was just > something which either was a bug or some unfortunate amount of short-term > memory utilization. This resulted in the following error: > WARN [StorageServiceShutdownHook] 2014-06-30 09:38:38,251 StorageProxy.java > (line 1713) Some hints were not written before shutdown. This is not > supposed to happen. You should (a) run repair, and (b) file a bug report > There are no other messages of relevance besides the OOM error about 90 > minutes earlier. > My (limited) understanding of the JVM and Cassandra says that when it goes > OOM, it will attempt to signal cassandra to shut down "cleanly". The problem, > in my view, is that with an OOM situation, nothing is guaranteed anymore. I > believe it's impossible to reliably "cleanly shut down" at this point, and > therefore it's wrong to even try. > Yes, ideally things could be written out, flushed to disk, memory messages > written, other nodes notified, etc. but why is there any reason to believe > any of those steps could happen? Would happen? Couldn't bad data be written > at this point to disk rather than good data? Some network messages delivered, > but not others? > I think Cassandra should have the option to (and possibly default) to kill > itself immediately upon the OOM condition happening in a hard way, and not > rely on the java-based clean shutdown process. Cassandra already handles > recovery from unclean shutdown, and it's not a big deal. My node, for > example, kept in a sort-of alive state for 90 minutes where who knows what it > was doing or not doing. > I don't know enough about the JVM and options for it to know the best exact > implementation of "die instantly on OOM", but it should be something that's > possible either with some flags or a C library (which doesn't rely on java > memory to do something which it may not be able to get!) > Short version: a kill -9 of all C* processes in that instance without needing > more java memory, when OOM is raised -- This message was sent by Atlassian JIRA (v6.3.4#6332)