RFR(XS): 8193521: glibc wastes memory with default configuration

[Andrew Dinn]

On 15/12/17 10:39, Doerr, Martin wrote:
> the behavior of the glibc can easily be traced by gdb.

Yes, indeed glibc is creating memory not needed /by the JVM/ as part
of creating the threads.

> The VM typically starts more than 20 threads even when only using
> java -version so we mmap several useless GB.

Well, that is the bone of contention here.

This space may be useless to the JVM code but it may not be useless to
other native code. If would be good if you could substantiate your claim
that this memory really is 'useless' (to all JVM users). Will your
proposed change damage performance for some users? If so then can we
scope the potential for damage and agree it is acceptable?

regards,


Andrew Dinn
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Senior Principal Software Engineer
Red Hat UK Ltd
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