RFR: 8246135: ZGC: Save important log lines and print them when dumping hs_err files

[Erik Österlund]

+1

/Erik

On 2020-06-02 09:55, Stefan Karlsson wrote:
> Found one more line that we should save:
>  https://cr.openjdk.java.net/~stefank/8246135/webrev.03.delta/
>  https://cr.openjdk.java.net/~stefank/8246135/webrev.03/
>
> StefanK
>
> On 2020-06-02 08:09, Stefan Karlsson wrote:
>> Thanks for reviewing.
>>
>> StefanK
>>
>> On 2020-06-01 20:50, stefan.johansson at oracle.com wrote:
>>> Hi Stefan,
>>>
>>> On 2020-06-01 16:38, Stefan Karlsson wrote:
>>>> Updated webrev:
>>>> https://cr.openjdk.java.net/~stefank/8246135/webrev.02
>>> Looks good, thanks for making the functionality shared. Filed 
>>> https://bugs.openjdk.java.net/browse/JDK-8246272 for the other GCs.
>>>
>>> Cheers,
>>> Stefan
>>>
>>>>
>>>> StefanJ asked if I could make this a utility that other GCs could 
>>>> use as well. I've moved the functionality to 
>>>> gc/shared/gcLogPrecious.[hc]pp, but I haven't implemented this for 
>>>> the other GCs. That part is left for separate RFEs.
>>>>
>>>> Thanks,
>>>> StefanK
>>>>
>>>> On 2020-05-29 12:23, Stefan Karlsson wrote:
>>>>> Hi all,
>>>>>
>>>>> Please review this patch to save some of the important ZGC log 
>>>>> lines and print them when dumping hs_err files.
>>>>>
>>>>> https://cr.openjdk.java.net/~stefank/8246135/webrev.01/
>>>>> https://bugs.openjdk.java.net/browse/JDK-8246135
>>>>>
>>>>> The patch adds a concept of "precious" log lines. What's typically 
>>>>> logged are GC initialization lines, but also error messages are 
>>>>> saved. These lines are then dumped in the hs_err file if the JVM 
>>>>> crashes or hits an assert. The lines can also be printed in a 
>>>>> debugger to get a quick overview when debugging.
>>>>>
>>>>> The precious lines are always saved, but just like any other 
>>>>> Unified Logging calls, only logged if the tags are enabled.
>>>>>
>>>>> The patch builds on the JDK-8246134 patch. The hs_err output looks 
>>>>> like this:
>>>>>
>>>>> ZGC Precious Log:
>>>>>  NUMA Support: Disabled
>>>>>  CPUs: 8 total, 8 available
>>>>>  Memory: 16384M
>>>>>  Large Page Support: Disabled
>>>>>  Medium Page Size: 32M
>>>>>  Workers: 5 parallel, 1 concurrent
>>>>>  Address Space Type: Contiguous/Unrestricted/Complete
>>>>>  Address Space Size: 65536M x 3 = 196608M
>>>>>  Min Capacity: 42M
>>>>>  Initial Capacity: 256M
>>>>>  Max Capacity: 4096M
>>>>>  Max Reserve: 42M
>>>>>  Pre-touch: Disabled
>>>>>  Uncommit: Enabled
>>>>>  Uncommit Delay: 300s
>>>>>  Runtime Workers: 5 parallel
>>>>>
>>>>> ZGC Globals:
>>>>>  GlobalPhase:       2 (Relocate)
>>>>>  GlobalSeqNum:      1
>>>>>  Offset Max:        4096G (0x0000040000000000)
>>>>>  Page Size Small:   2M
>>>>>  Page Size Medium:  32M
>>>>>
>>>>> ZGC Metadata Bits:
>>>>>  Good:              0x0000100000000000
>>>>>  Bad:               0x00002c0000000000
>>>>>  WeakBad:           0x00000c0000000000
>>>>>  Marked:            0x0000040000000000
>>>>>  Remapped:          0x0000100000000000
>>>>>
>>>>> Heap:
>>>>>  ZHeap           used 12M, capacity 256M, max capacity 4096M
>>>>>  Metaspace       used 6501K, capacity 6615K, committed 6784K, 
>>>>> reserved 1056768K
>>>>>   class space    used 559K, capacity 588K, committed 640K, 
>>>>> reserved 1048576K
>>>>>
>>>>> ZGC Page Table:
>>>>>  Small   0x0000000000000000 0x0000000000200000 0x0000000000200000 
>>>>> Allocating
>>>>>  Small   0x0000000000200000 0x0000000000240000 0x0000000000400000 
>>>>> Allocating
>>>>>  Small   0x0000000000400000 0x0000000000600000 0x0000000000600000 
>>>>> Allocating
>>>>>  Small   0x0000000000600000 0x0000000000800000 0x0000000000800000 
>>>>> Allocating
>>>>>  Small   0x0000000000800000 0x00000000009c0000 0x0000000000a00000 
>>>>> Allocating
>>>>>  Small   0x0000000000a00000 0x0000000000a40000 0x0000000000c00000 
>>>>> Allocating
>>>>>
>>>>> Thanks,
>>>>> StefanK
>>>>
>>
>