Code review request: CR 6995781 Native Memory Tracking Phase 1

[Zhengyu Gu]

Vladimir,

I did find that compiler sometimes uses Arenas as value or stack 
objects,  they are actually tracked through Arena::set_size_in_bytes(), 
only they can not be categorized, so you may see "Unknown" category.

Thread resource areas are malloc'd arenas, they should already be 
tracked. GrowableArray is tracked through c-heap allocation (c-heap 
type), arena or resource area.

Please let me know if I missed anything, and could you point me a few 
instances?

Thanks,

-Zhengyu

On 6/13/2012 2:15 PM, Vladimir Kozlov wrote:
> Zhengyu,
>
> You missed a lot of places in JIT compilers, c1 and opto, where we use 
> arenas, thread resource areas, GrowableArrays. Could be because some 
> arenas are embedded like _comp_arena. Compilers can eat several 
> hundreds MBytes easily.
>
> Is it possible to implement lightweight of this to turn it ON always 
> to dump usage info into hs_err file when VM crash? You don't need to 
> track PC for that, only total usage by MemoryType. It would be very 
> useful because we see a lot of OOM crashes recently (we have it in 
> each Nightly testing).
>
> Thanks,
> Vladimir
>
> Zhengyu Gu wrote:
>> This is the webrev for native memory tracking phase 1, which is 
>> tracked by CR6995781 
>> (http://monaco.us.oracle.com/detail.jsf?cr=6995781) and related DCmd 
>> CR7151532 (http://monaco.us.oracle.com/detail.jsf?cr=7151532).
>>
>> Native memory tracking (NMT) phase 1, is designed to track native 
>> memory (malloc'd and mmap'd) usages by VM code only, it does not 
>> track the memory usages by libraries and JNI code.
>>
>> On the implementation side, NMT intercepts memory related calls in os 
>> implementation, such as os::malloc, os::realloc, os::free, 
>> os::reserve_memory, os::commit_memory and etc. the caller is required 
>> to provide the 'memory type' information, which represents the VM 
>> subsystem that the memory is allocated for. The 'memory type' is 
>> defined in /src/share/memory/allocation.hpp. Also, a caller's pc is 
>> captured if NMT tracking level is set to detail.
>>
>> There are a few ways to tag a memory block to a memory type:
>>
>> 1. os::malloc takes an extra parameter for the memory type.
>> 2. CHeapObj now is a template, it takes a memory type as template 
>> parameter to tag the object to a specified memory type.
>> 3. Utility classes, such as Arena, GrowableArray and etc. the memory 
>> type is a parameter of 'new' operator.
>> 4. Virtual memory block is tagged on its base address.
>>
>> When NMT intercepts the call, a memory record is created and 
>> serialized by a sequence number, generated by global sequence 
>> generator. The memory record is written to a per-thread recorder 
>> without a  lock, when calling thread is a 'safepoint visible' 
>> JavaThread - a JavaThread that will block at safepoint. Otherwise, 
>> ThreadCritical lock is acquired to write to a global recorder. The 
>> recorders (or raw data) are synchronized at some safepoints, and 
>> global sequence generator is also reset at synchronization time, to 
>> avoid overflow the sequence number.
>>
>> A dedicated NMT worker thread is created to process the raw memory 
>> records. It first stages a generation of raw data (a generation is 
>> defined as span between resets of global sequence number), then 
>> promotes the staged data to a global snapshot, which maintains 
>> information of all 'live' memory block.
>>
>> NMT Tracking option has to be specified through VM command line 
>> option -XX:NativeMemoryTracking (off by default), tracking level can 
>> not be altered during runtime, but it can be shutdown through jcmd tool.
>>
>> NMT DCmd implements a set of sub-command to control NMT runtime and 
>> request tracking data.
>>
>> Webrev: http://cr.openjdk.java.net/~zgu/6995781/webrev.00
>>
>> The tests and results:
>>
>>  - Passed internal smoke tests
>>  - JTreg test: http://cr.openjdk.java.net/~zgu/6995781/JTreport/
>>
>>
>> Additional notes:
>>   - Some classes' new operators are marked _NOINLINE_ (for the same 
>> purpose as above), the performance runs, I performed, indicate that 
>> they do not impact performance numbers.
>>
>>   - SA agent changes are in progress
>>
>> Thanks,
>>
>> -Zhengyu
>>
>>
>>
>>