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

[Stefan Karlsson]

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
>>>
>