RFR(S) 8233826 Change CDS dumping tty->print_cr() to unified logging
coleen.phillimore at oracle.com
coleen.phillimore at oracle.com
Thu Dec 19 17:01:15 UTC 2019
Hi Jiangli,
On 12/18/19 7:34 PM, Jiangli Zhou wrote:
> Hi Coleen,
>
> On Wed, Dec 18, 2019 at 1:45 PM <coleen.phillimore at oracle.com> wrote:
>>
>>
>> On 12/18/19 12:35 PM, Jiangli Zhou wrote:
>>> On Wed, Dec 18, 2019 at 9:09 AM Ioi Lam <ioi.lam at oracle.com> wrote:
>>>> On 12/18/19 7:49 AM, Jiangli Zhou wrote:
>>>>> The default dumping output provides useful information, particularly
>>>>> with static archiving.
>>>> Hi Jiangli,
>>>>
>>>> Thanks for looking this patch.
>>>>
>>>> This patch affects only "informational" messages. It doesn't affect the
>>>> warning/error messages, which I think are the ones that users want to see.
>>>>
>>>> I agree that the informational messages are useful for developers of CDS
>>>> (I look at them all the time). However, I don't know if any of the
>>>> following messages would be useful to a user of CDS. These messages are
>>>> not printed during dynamic dumping, and no one has complained.
>>>>
>>> The number of archived classes and arrays, the size of the archive and
>>> etc are all useful information for users of static CDS dumping. If
>>> there is any failure, the output also provides helpful information for
>>> isolating when failure occurs.
>>>
>>>> $ java -Xshare:dump
>>>> Allocated shared space: 3221225472 bytes at 0x0000000800000000
>>>> Loading classes to share ...
>>>> Loading classes to share: done.
>>>> Reading extra data: done.
>>>> Rewriting and linking classes ...
>>>> Rewriting and linking classes: done
>>>> Number of classes 1258
>>>> instance classes = 1192
>>>> obj array classes = 58
>>>> type array classes = 8
>>>> Updating ConstMethods ... done.
>>>> Removing unshareable information ... done.
>>>> Scanning all metaspace objects ...
>>>> Allocating RW objects ...
>>>> Allocating RO objects ...
>>>> Relocating embedded pointers ...
>>>> Relocating external roots ...
>>>> Dumping symbol table ...
>>>> Dumping objects to closed archive heap region ...
>>>> Dumping objects to open archive heap region ...
>>>> Relocating SystemDictionary::_well_known_klasses[] ...
>>>> Removing java_mirror ... done.
>>>> mc space: 8728 [ 0.1% of total] out of 12288 bytes [ 71.0%
>>>> used] at 0x0000000800000000
>>>> rw space: 4089896 [ 32.2% of total] out of 4091904 bytes [100.0%
>>>> used] at 0x0000000800003000
>>>> ro space: 7546512 [ 59.4% of total] out of 7548928 bytes [100.0%
>>>> used] at 0x00000008003ea000
>>>> md space: 2272 [ 0.0% of total] out of 4096 bytes [ 55.5%
>>>> used] at 0x0000000800b1d000
>>>> bm space: 184320 [ 1.5% of total] out of 184320 bytes [100.0%
>>>> used] at 0x0000000000000000
>>>> ca0 space: 520192 [ 4.1% of total] out of 520192 bytes [100.0%
>>>> used] at 0x00000007bfc00000
>>>> oa0 space: 339968 [ 2.7% of total] out of 339968 bytes [100.0%
>>>> used] at 0x00000007bf800000
>>>> total : 12689192 [100.0% of total] out of 12701696 bytes [ 99.9% used]
>>>>
>>>>
>>>>
>>>>> Developers may not know which logging option
>>>>> needs to be specified to enable the output.
>>>>>
>>>>> One possible solution is to enable -Xlog:cds by default for
>>>>> -Xshare:dump, if the output method is converted to use unified
>>>>> logging.
>>>> I suppose if someone is interested, they can find out the tag
>>>> information by reading the documentation? That's the same if you want to
>>>> see the logs for other VM features such as gc or class loading.
>>> The above does not seem to be a safe assumption. The less burden that
>>> we place on Java developers the better.
>>>
>>> From a usability point of view, I think the output should be enabled
>>> by default.
>> The Unified Logging system was added to the VM so that all the JVM
>> output used the same mechanism. Having a knowlegable user specify
>> -Xlog:cds doesn't seem burdensome.
>>
> Average Java developers may not have the detailed/ and right knowledge
> about the logging system(?).
I don't believe that. Logging's been in the system since JDK 9, and
it's pretty intuitive.
>
>> To me, the output has always looked like logging, and not simply
>> printing that it succeeded. Also the size percentage output seems less
>> meaningful now that the archive is compacted before dumping. Most of
>> this information is only useful for developers and should be -Xlog:cds=info.
>>
> With Ioi's current change in place, -Xshare:dump now produce no
> output. To be able to see any dumping output even for confirmation
> purpose, users now need to add -Xlog:cds option explicitly. The
> -Xlog:cds gives the original default dumping output and some
> additional information. If we can cleanup the -Xlog:cds logging info
> by removing the 'Shared file region 4: 0x0002dc18 bytes...' related
> output, we can still give user useful and not overwhelming
> information, by enabling it by default for -Xshare:dump. It would also
> help users to avoid having to type -Xlog:cds when they
> experimenting/using with the feature manually. Any particular reason
> or concern for not going with that?
>
> $ bin/java -Xshare:dump
>
> $ bin/java -Xshare:dump -Xlog:cds
> [0.028s][info][cds] narrow_klass_base = 0x0000000800000000,
> narrow_klass_shift = 3
> [0.028s][info][cds] Allocated temporary class space: 1073741824 bytes
> at 0x00000008c0000000
> [0.028s][info][cds] Allocated shared space: 3221225472 bytes at
> 0x0000000800000000
> [0.417s][info][cds] Loading classes to share ...
> [1.020s][info][cds] Loading classes to share: done.
> [1.020s][info][cds] Shared spaces: preloaded 1187 classes
> [1.020s][info][cds] Reading extra data: done.
> [1.026s][info][cds] Rewriting and linking classes ...
> [1.126s][info][cds] Rewriting and linking classes: done
> [2.077s][info][cds] Number of classes 1261
> [2.077s][info][cds] instance classes = 1195
> [2.077s][info][cds] obj array classes = 58
> [2.077s][info][cds] type array classes = 8
> [2.077s][info][cds] Updating ConstMethods ...
> [2.141s][info][cds] done.
> [2.141s][info][cds] Removing unshareable information ...
> [2.203s][info][cds] done.
> [2.226s][info][cds] Scanning all metaspace objects ...
> [2.226s][info][cds] Allocating RW objects ...
> [2.552s][info][cds] Allocating RO objects ...
> [2.916s][info][cds] Relocating embedded pointers ...
> [3.518s][info][cds] Relocating external roots ...
> [3.580s][info][cds] Verifying external roots ...
> [3.627s][info][cds] Dumping symbol table ...
> [3.693s][info][cds] Dumping objects to closed archive heap region ...
> [3.775s][info][cds] Dumping objects to open archive heap region ...
> [3.863s][info][cds] Relocating SystemDictionary::_well_known_klasses[] ...
> [3.863s][info][cds] Removing java_mirror ...
> [3.863s][info][cds] done.
> [3.868s][info][cds] Oopmap = 0x0000000800b705c0 ( 16256 bytes) for
> heap region 0x00000007ffc00000 ( 520192 bytes)
> [3.870s][info][cds] Oopmap = 0x0000000800b74540 ( 10624 bytes) for
> heap region 0x00000007ff800000 ( 339968 bytes)
> [3.880s][info][cds] Dumping shared data to file:
> [3.880s][info][cds]
> /usr/local/google/home/jianglizhou/openjdk/jdk/build/linux-x86_64-server-slowdebug/images/jdk/lib/server/classes.jsa
Here.
> [3.880s][info][cds] Shared file region 0: 0x000058d8 bytes, addr
> 0x0000000800000000 file offset 0x00001000
> [3.880s][info][cds] Shared file region 1: 0x00436528 bytes, addr
> 0x0000000800006000 file offset 0x00007000
> [3.885s][info][cds] Shared file region 2: 0x00739ec0 bytes, addr
> 0x000000080043d000 file offset 0x0043e000
> [3.895s][info][cds] Shared file region 3: 0x000009a0 bytes, addr
> 0x0000000800b77000 file offset 0x00b78000
> [3.895s][info][cds] ptrmap = 0x00007fe961b5a230 (187416 bytes)
> [3.895s][info][cds] Shared file region 4: 0x0002dc18 bytes, addr
> 0x0000000000000000 file offset 0x00b79000
> [3.895s][info][cds] Archive heap region 5: 0x00000007ffc00000 -
> 0x00000007ffc7f000 = 520192 bytes
> [3.895s][info][cds] Shared file region 5: 0x0007f000 bytes, addr
> 0x00000007ffc00000 file offset 0x00ba7000
> [3.896s][info][cds] Archive heap region 6: 0x0000000000000000 -
> 0x0000000000000000 = 0 bytes
> [3.896s][info][cds] Shared file region 6: 0x00000000 bytes, addr
> 0x0000000000000000 file offset 0x00c26000
> [3.896s][info][cds] Archive heap region 7: 0x00000007ff800000 -
> 0x00000007ff853000 = 339968 bytes
> [3.896s][info][cds] Shared file region 7: 0x00053000 bytes, addr
> 0x00000007ff800000 file offset 0x00c26000
> [3.896s][info][cds] Archive heap region 8: 0x0000000000000000 -
> 0x0000000000000000 = 0 bytes
> [3.896s][info][cds] Shared file region 8: 0x00000000 bytes, addr
> 0x0000000000000000 file offset 0x00c79000
> [3.896s][info][cds] mc space: 22744 [ 0.2% of total] out of
> 24576 bytes [ 92.5% used] at 0x0000000800000000
> [3.896s][info][cds] rw space: 4416808 [ 33.8% of total] out of
> 4419584 bytes [ 99.9% used] at 0x0000000800006000
> [3.896s][info][cds] ro space: 7577280 [ 58.0% of total] out of
> 7577600 bytes [100.0% used] at 0x000000080043d000
> [3.896s][info][cds] md space: 2464 [ 0.0% of total] out of
> 4096 bytes [ 60.2% used] at 0x0000000800b77000
> [3.896s][info][cds] bm space: 188416 [ 1.4% of total] out of
> 188416 bytes [100.0% used] at 0x0000000000000000
> [3.896s][info][cds] ca0 space: 520192 [ 4.0% of total] out of
> 520192 bytes [100.0% used] at 0x00000007ffc00000
> [3.896s][info][cds] oa0 space: 339968 [ 2.6% of total] out of
> 339968 bytes [100.0% used] at 0x00000007ff800000
> [3.896s][info][cds] total : 13066872 [100.0% of total] out of
> 13074432 bytes [ 99.9% used]
> [3.896s][info][cds] Detailed metadata info (excluding st regions; rw
> stats include md/mc regions):
> [3.896s][info][cds] ro_cnt ro_bytes % |
> rw_cnt rw_bytes % | all_cnt all_bytes %
> [3.896s][info][cds]
> --------------------+---------------------------+---------------------------+--------------------------
> [3.896s][info][cds] Class : 0 0 0.0 |
> 1261 843432 19.0 | 1261 843432 7.0
> [3.896s][info][cds] Symbol : 37883 1491992 19.7 |
> 0 0 0.0 | 37883 1491992 12.4
> [3.896s][info][cds] TypeArrayU1 : 9274 275872 3.6 |
> 1195 244616 5.5 | 10469 520488 4.3
> [3.896s][info][cds] TypeArrayU2 : 3093 161104 2.1 |
> 0 0 0.0 | 3093 161104 1.3
> [3.896s][info][cds] TypeArrayU4 : 1370 87216 1.2 |
> 0 0 0.0 | 1370 87216 0.7
> [3.896s][info][cds] TypeArrayU8 : 2045 188936 2.5 |
> 1195 142840 3.2 | 3240 331776 2.8
> [3.896s][info][cds] TypeArrayOther : 0 0 0.0 |
> 0 0 0.0 | 0 0 0.0
> [3.896s][info][cds] Method : 0 0 0.0 |
> 19089 1992200 44.8 | 19089 1992200 16.6
> [3.896s][info][cds] ConstMethod : 19089 2956768 39.0 |
> 0 0 0.0 | 19089 2956768 24.6
> [3.896s][info][cds] MethodData : 0 0 0.0 |
> 0 0 0.0 | 0 0 0.0
> [3.896s][info][cds] ConstantPool : 1195 1942912 25.6 |
> 0 0 0.0 | 1195 1942912 16.2
> [3.896s][info][cds] ConstantPoolCache : 0 0 0.0 |
> 1195 1193720 26.9 | 1195 1193720 9.9
> [3.896s][info][cds] Annotations : 59 1888 0.0 |
> 0 0 0.0 | 59 1888 0.0
> [3.896s][info][cds] MethodCounters : 0 0 0.0 |
> 0 0 0.0 | 0 0 0.0
> [3.896s][info][cds] RecordComponent : 0 0 0.0 |
> 0 0 0.0 | 0 0 0.0
> [3.896s][info][cds] SymbolHashentry : 37883 300216 4.0 |
> 0 0 0.0 | 37883 300216 2.5
> [3.896s][info][cds] SymbolBucket : 9470 37888 0.5 |
> 0 0 0.0 | 9470 37888 0.3
> [3.896s][info][cds] StringHashentry : 7227 57320 0.8 |
> 0 0 0.0 | 7227 57320 0.5
> [3.896s][info][cds] StringBucket : 1806 7232 0.1 |
> 0 0 0.0 | 1806 7232 0.1
> [3.896s][info][cds] Other : 0 67936 0.9 |
> 0 25208 0.6 | 0 93144 0.8
> [3.896s][info][cds]
> --------------------+---------------------------+---------------------------+--------------------------
> [3.896s][info][cds] Total : 130394 7577280 100.0 |
> 23935 4442016 100.0 | 154329 12019296 100.0
>
Actually, I partially agree with this. I think the table at the end,
and maybe even the shared region %ages part could be -Xlog:cds=debug,
but all of the output should be under -Xlog:cds={info,debug}.
Someone experimenting with CDS should absolutely already know about
-Xlog:cds. That's not a stretch. We're trying to get to the jvm not
having any tty->print() anymore, and all output is controlled so that
users can choose what they see. UL is nice that you have this
flexibility to see what you want.
So I agree that making the last part of the output -Xlog:cds=debug or
even -Xlog:cds+regions=info.
thanks,
Coleen
> Best,
> Jiangli
>
>> Thanks,
>> Coleen
>>
>>> Regards,
>>> Jiangli
>>>
>>>> Thanks
>>>> - Ioi
>>>>
>>>>> Regards,
>>>>> Jiangli
>>>>>
>>>>> On Tue, Dec 17, 2019 at 10:34 PM Ioi Lam <ioi.lam at oracle.com> wrote:
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8233826
>>>>>> http://cr.openjdk.java.net/~iklam/jdk15/8233826-cds-change-tty-to-ul.v01/
>>>>>>
>>>>>> During CDS dumping, a few messages are printed out unconditionally
>>>>>> using tty->print_cr(). This patch changes the message to use
>>>>>> log_info(cds) instead.
>>>>>>
>>>>>> Some test cases were expecting the messages in stdout. I modified
>>>>>> these tests to explicitly pass -Xlog:cds.
>>>>>>
>>>>>> Thanks
>>>>>> - Ioi
>>>>>>
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