RFR rev1 (M): 8078556: Runtime: implement ranges (optionally constraints) for those flags that have them missing (original) (raw)

gerard ziemski gerard.ziemski at oracle.com
Wed Oct 14 15:31:41 UTC 2015

hi Goetz,

Great work, thank you for all the feedback, please see my answers inline:

On 10/14/2015 04:00 AM, Lindenmaier, Goetz wrote:

Hi Gerald,

I had a closer look at your change now, especially on the settings of the stack protection zone sizes. You set the lower bounds of the stack protection pages > 1. Because of that the VM on PPC does not start up, it immediately fails with: intx StackYellowPages=1 is outside the allowed range [ 6 ... 11 ] intx StackShadowPages=1 is outside the allowed range [ 8 ... 38 ] Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit. The lower bounds of these flags must be '1'. If vmpagesize() > vmdefaultpagesize(), the numbers of pages are reduced. This is necessary on systems with page size 64K, else stacks get too big. We have such systems on ppc. See also oslinux.cpp:4649.

PPC issue I will have to comment on later.

http://cr.openjdk.java.net/~gziemski/8078556rev2/src/cpu/sparc/vm/globalssparc.hpp.udiff.html Why do you need to special-case for !LP64 on sparc? As I understand, this is no more supported in jdk9.

I'd prefer to keep the code in for completeness for those who will be reading that header.

in globals.hpp: http://cr.openjdk.java.net/~gziemski/8078556rev2/src/share/vm/runtime/globals.hpp.udiff.html

You might want to use SIZEMAX for MaxDirectMemorySize: _product(sizet, MaxDirectMemorySize, 0, _ _+ range(0, (sizet)maxuintx) _

I like that. I will see if all the platforms are happy with SIZE_MAX

This lower bound setting crashes the VM on linuxx8664 and seems pointless: _productpd(intx, ThreadStackSize, _ _+ range(0, maxintx-os::vmpagesize()) _ bin/java -XX:ThreadStackSize=0 # Internal Error (.../src/os/linux/vm/oslinux.cpp:720), pid=47259, tid=47260 # assert(JavaThread::stacksizeatcreate() > 0) failed: this should be set

Yes, this is a follow-up issue tracked by https://bugs.openjdk.java.net/browse/JDK-8136766

More crashes I see on linuxx8664: bin/java -XX:MallocMaxTestWords=1 # There is insufficient memory for the Java Runtime Environment to continue. # Native memory allocation (malloc) failed to allocate 18 bytes for AllocateHeap

Right, this flag will be disabled from testing by the runtime/CommandLine/OptionsValidation as the valid values are in fact allowed to crash the VM for testing purposes, which is a behavior that can not be captured by the testing framework at the moment.

bin/java -XX:VMThreadStackSize=9007199254740991 / 4294967296 / 2147483648 # There is insufficient memory for the Java Runtime Environment to continue. # Cannot create worker GC thread. Out of system resources.

"Out of system resources" errors are in fact allowed. Still, is this a crash that dumps an error log? I do not see this issue in our internal testing, but I will verify on my local 64bit Linux (Ubuntu 14.04)

and on linuxppc64: /sapmnt/home/d045726/oJ/vms/ppc9-1/bin/java -XX:MaxRAM=18446744073709551615 OpenJDK 64-Bit Server VM warning: INFO: os::commitmemory(0x0000000082000000, 32178700288, 0) failed; error='Cannot allocate memory' (errno=12) # There is insufficient memory for the Java Runtime Environment to continue. # Native memory allocation (mmap) failed to map 32178700288 bytes for committing reserved memory.

PPC issue I will have to comment on later.

I saw these errors trying to run runtime/CommandLine/OptionsValidation/TestOptionsWithRanges.java with a debug build.

If you need any more input, especially on ppc, I'm happy to help out!

That would be great! I will reach out to you regarding PPC support after I look into it more.

Big thank you for the review!

cheers

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