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Patrick Hunt commented on ZOOKEEPER-759: ---------------------------------------- Is there anything comparable on the windows jvm, or no options at all on that platform? What about alternative (non sun) jvms? Guess we treat those similar to windows... we should think about it when implementing though. > Stop accepting connections when close to file descriptor limit > -------------------------------------------------------------- > > Key: ZOOKEEPER-759 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-759 > Project: Zookeeper > Issue Type: Improvement > Components: server > Reporter: Travis Crawford > > Zookeeper always tries to accept new connections, throwing an exception if > out of file descriptors. An improvement would be denying new client > connections when close to the limit. > Additionally, file-descriptor limits+usage should be exported to the > monitoring four-letter word, should that get implemented (see ZOOKEEPER-744). > DETAILS > A Zookeeper ensemble I administer recently suffered an outage when one node > was restarted with the low system-default ulimit of 1024 file descriptors and > later ran out. File descriptor usage+max are already being monitored by the > following MBeans: > - java.lang.OperatingSystem.MaxFileDescriptorCount > - java.lang.OperatingSystem.OpenFileDescriptorCount > They're described (rather tersely) at: > http://java.sun.com/javase/6/docs/jre/api/management/extension/com/sun/management/UnixOperatingSystemMXBean.html > This feature request is for the following: > (a) Stop accepting new connections when OpenFileDescriptorCount is close to > MaxFileDescriptorCount, defaulting to 95% FD usage. New connections should be > denied, logged to disk at debug level, and increment a > ``ConnectionDeniedCount`` MBean counter. > (b) Begin accepting new connections when usage drops below some configurable > threshold, defaulting to 90% of FD usage, basically the high/low watermark > model. > (c) Update the administrators guide with a comment about using an appropriate > FD limit. > (d) Extra credit: if ZOOKEEPER-744 is implemented export statistics for: > zookeeper_open_file_descriptor_count > zookeeper_max_file_descriptor_count > zookeeper_max_file_descriptor_mismatch - boolean, exported by leader, if not > all zk's have the same max FD value -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.