RFR(S) 8233826 Change CDS dumping tty->print_cr() to unified logging
Ioi Lam
ioi.lam at oracle.com
Thu Dec 19 19:08:32 UTC 2019
Hi Jiangli & Coleen,
Thanks for the comments. I agree with both of you that the -Xlog:cds "info"
output is too verbose, so I moved the ones you suggested into the
"debug" log.
Coleen, I used -Xlog:cds=debug instead of -Xlog:cds+regions=info,
because there's
no current log of the cds+regions combination. My experience with have a
minor
combination like that is people (including me) will forget about it, and
will end up using -Xlog:cds*=info, which produces too much output.
Here's the update from the last webrev:
http://cr.openjdk.java.net/~iklam/jdk15/8233826-cds-change-tty-to-ul.v02.delta/
Sample output:
java -Xshare:dump -Xlog:cds
http://cr.openjdk.java.net/~iklam/jdk15/8233826-cds-change-tty-to-ul.v02.delta/log_cds.txt
java -Xshare:dump -Xlog:cds=debug
http://cr.openjdk.java.net/~iklam/jdk15/8233826-cds-change-tty-to-ul.v02.delta/log_cds_debug.txt
Thanks
- Ioi
On 12/19/2019 9:01 AM, coleen.phillimore at oracle.com wrote:
>
> 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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