RFR: (S): JDK-8200613: SA: jstack throws UnmappedAddressException with a CDS core file (original) (raw)

Jini George jini.george at oracle.com
Tue Oct 9 06:01:52 UTC 2018

Hello!

[Including runtime-dev since the changes are in runtime code]

Requesting reviews for:

Webrev: http://cr.openjdk.java.net/~jgeorge/8200613/webrev.01/ BugID: https://bugs.openjdk.java.net/browse/JDK-8200613

Issue: jhsdb jstack would throw an UnmappedAddressException with a core file generated from a CDS enabled java process. This is seen only with Linux and with G1GC, while trying to read in data from the shared strings region (the closed archive heap space). This region (which is a file backed private memory region) is not dumped into the corefile for Linux. This, being a heap region (and therefore being a read-write region) is also not read in from the classes.jsa file in SA since only the read only regions are read in while processing the core file. (The expectation being that the read write regions are in the core file).

Proposed solution: The proposed solution is to have the coredump_filter value corresponding to the CDS process to include bit 2 (file-backed private memory), so that the file-backed private memory region also gets dumped into the corefile. The proposed fix is in src/hotspot/os/linux/os_linux.cpp.

Thanks, Jini.

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