1.6.0-b105 Server VM much slower than 18.104.22.168 -- Huge total compile time
We have a fairly complex application originally written for Java 5 that runs about 2.5x slower on the 1.6.0-b105 Server VM than under the 22.214.171.124 Server VM (measured a long time after startup, so we think the HotSpot warm-up time is factored out of this). We also see that the "Total compile time" shown in jconsole for 1.6 is huge. For example, from jconsole:
Uptime: 1 hour 1 minute
Process CPU time: 51 minutes
JIT Compiler: HotSpot Server Compiler
Total compile time: 53 minutes
Under 126.96.36.199, the total compile time is 6-10 minutes for this total duration. One possibility is that the measurement of the total compile time is just plain broken (as might be indicated by discrepancy between 51 and 53 minutes), but I suspect there really is an underlying problem since the application runs so much slower under 1.6.
The application uses about 220 threads to send and receive JMS messages (implemented through ActiveMQ) and perform lots of disk I/O to store and retrieve files. We spend a significant amount of CPU time compressing and encrypting the data stored in the files. We have loaded about 4,025 classes and have unloaded only 70 classes in the first hour of operation, so I don't think we are creating or loading an excessive number of new classes. The issue does not appear to be related to gc; we have spent only 1 minute in garbage collection in the first hour of run time. The application has created new threads at the rate of about 2 per second for the duration of the test, but this also happens when we run it under 188.8.131.52.
Thinking we might be exhausting the compiled code cache I set -XX:ReservedCodeCacheSize to 128m with no apparent effect. Are there any other VM settings we should try?
Many thanks in advance for any help or suggestions.