For testing purposes, I want to run multiple instances of Hazelcast on a single node. Hazelcast assumes that it is managing the entire node, and therefore it creates a large enough number of threads to fully (in fact, over) load all the cores. On my 8-core Linux node, Hazelcast creates 74 threads per instance, which quickly runs up against the user thread limit. (Yes, I know this can be changed with ulimit.)
From jconsole threads view:
- hz.hzInstance_1_dev.scheduled
- hz.hzInstance_1_dev.generic-operation.thread (x16)
- hz.hzInstance_1_dev.partition-operation.thread (x16)
- hz.hzInstance_1_dev.response
- hz.hzInstance_1_dev.event (x5)
- hz.hzInstance_1_dev.wait-notify
- hz.hzInstance_1_dev.wan (x16)
- hz.hzInstance_1_dev.cached.thread
- hz.hzInstance_1_dev.migration
- hz.hzInstance_1_dev.IO-thread-in (x3)
- hz.hzInstance_1_dev.IO-thread-out (x3)
- hz.hzInstance_1_dev.IO-thread-Acceptor
- hz.hzInstance_1_dev.cached-thread (x8)
- hz.hzInstance_1_dev.HealthMonitor
Some of the thread counts can be reduced by setting Hazelcast system properties:
- generic-operation.thread =
hazelcast.operation.generic.thread.count - partition-operation.thread =
hazelcast.operation.thread.count - IO-thread =
hazelcast.io.thread.count - event =
hazelcast.event.thread.count
The default numbers of wan, generic-operation and partition-operation threads are all 2 x CPU core count. There doesn't appear to be any way to reduce the number of wan threads.
Is there a way to specify how many cores Hazelcast should use, rather than specifying generic-operation.thread and partition-operation.thread separately? Setting CPU affinity doesn't work, as Hazelcast still thinks it has access to all the cores.
Is there any way to change the number of WAN replication threads?
