RFR: 8247536: Support for pre-generated java.lang.invoke classes in CDS static archive

David Holmes david.holmes at oracle.com
Tue Aug 18 02:34:34 UTC 2020


Hi Sundar,

On 18/08/2020 12:25 pm, sundararajan.athijegannathan at oracle.com wrote:
> Not a full review of fresh changes. But couple of comments:
> 
> * src/hotspot/share/memory/lambdaFormInvokers.cpp and 
> src/hotspot/share/memory/lambdaFormInvokers.hpp miss "Classpath 
> exception" clause in the copyright header

Hotspot files do not use the Classpath exception. That is for .java 
sources that will be"linked against" by applications.

Cheers,
David

> * I had suggested a change GenerateJLIClassesPlugin.java in last round 
> of review. That's still applicable.
> 
> https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-August/068160.html 
> 
> 
> -Sundar
> 
> On 18/08/20 1:07 am, Yumin Qi wrote:
>> Hi, Ioi
>>
>>   Thanks for review/suggestion. I have updated the webrev at the 
>> following link:
>>
>> http://cr.openjdk.java.net/~minqi/2020/8247536/webrev-02/
>>
>>   Following changes done in this patch:
>>
>>   1) move regenerating holder classes into new added file: 
>> lambdaFormInvokers.[ch]pp
>>
>>   "@lambda-form-invoker" tag only observed at jvm side.
>>
>>   2) remove InvokerBytecodeGeneratorHelper.java, move related 
>> functions to existing class, GenerateJLIClassesHelper.java
>>
>>   3) add tracing for SPECIES_RESOLVE, so archive more classes.
>>
>>   4) remove InvokerGenerateBytesException.java, using RuntimeException 
>> instead.
>>
>>   5) Changed make file to exclude the new added lamdaFormInvokers.cpp 
>> from the non-cds building list.
>>
>>   6) There is a bug in previous patch, jobject (typeArrayOop) should 
>> not be used directly for loading class since GC will move the java 
>> object. Fixed by copying the bytes from handle to C heap.
>>
>>   7) Tested with tier1,2
>>
>>
>> Thanks
>>
>> Yumin
>>
>>
>>
>> On 8/15/20 6:27 PM, Ioi Lam wrote:
>>> On 8/15/20 6:19 PM, Ioi Lam wrote:
>>>> To better capture what we're trying to do in this RFE, I've changed 
>>>> the RFE title (and the subject of this email thread) to
>>>>
>>>> https://bugs.openjdk.java.net/browse/JDK-8247536
>>>> Support for pre-generated java.lang.invoke classes in CDS static 
>>>> archive
>>>>
>>>> I also update the RFE Description to give an overview of the problem 
>>>> and the solution.
>>>>
>>>> The design document is also updated to reflect Yumin's latest 
>>>> implementation
>>>>
>>>
>>> Oops, sent too quickly. The design doc's title is also updated:
>>>
>>> https://wiki.openjdk.java.net/display/HotSpot/Support+for+pre-generated+java.lang.invoke+classes+in+CDS+archive 
>>>
>>>
>>>> Thanks
>>>> - Ioi
>>>>
>>>> On 8/12/20 11:54 AM, calvin.cheung at oracle.com wrote:
>>>>> Hi Yumin,
>>>>>
>>>>> I reviewed mostly the native code. Below are my comments:
>>>>>
>>>>> 1) classListParser.hpp
>>>>>
>>>>> 71   bool                _lambda_format;
>>>>>
>>>>> The above name is too generic. How about _lambda_form or 
>>>>> _is_lambda_form?
>>>>> If you rename the above, please also rename the function which 
>>>>> returns the above bool.
>>>>>
>>>>> 2) jvm.cpp
>>>>>
>>>>> 3850 JVM_ENTRY(void, JVM_CDSTraceResolve(JNIEnv* env, jclass 
>>>>> ignore, jstring line))
>>>>>
>>>>> ignore -> ignored
>>>>>
>>>>> 3) jvm.hpp
>>>>>
>>>>> 210 JVM_CDSTraceResolve(JNIEnv* env, jclass ignore, jstring line);
>>>>>
>>>>> Same comment as for jvm.cpp
>>>>>
>>>>> 4) metaspaceShared.cpp
>>>>>
>>>>> 2017   size_t i = 0;
>>>>> 2018   while (i < size) {
>>>>> 2019     full_name[i++] = *start++;
>>>>> 2020   }
>>>>>
>>>>> Could the above be simplified to the following?
>>>>>
>>>>>     strncpy(full_name, start, size - 1);
>>>>>
>>>>> 2029   char* class_name = get_full_class_name(path_name);
>>>>>
>>>>> Should os::free(class_name) be called before the function returns?
>>>>>
>>>>> 1870 static GrowableArray<char *>* lambda_list = NULL;
>>>>>
>>>>> The name lambda_list is a bit generic, how about lambda_form_list?
>>>>>
>>>>> 2112       lambda_list->append(parser.current_line());
>>>>>
>>>>> Since parser.current_line() does a strdup, do those buffer need to 
>>>>> be freed after its use? (i.e. after the call to 
>>>>> regenerate_holder_classes()?)
>>>>>
>>>>> In MetaspaceShared::regenerate_holder_classes, before calling up to 
>>>>> java, I think it's better to strip the prefix 
>>>>> "@lambda-form-invoker" from the strings. So that the java 
>>>>> InvokerBytecodeGeneratorHelper.readTraceConfig method doesn't need 
>>>>> to handle it:
>>>>>
>>>>>  143                     case "[LF_RESOLVE]":
>>>>>  144                     case InvokerBytecodeGenerator.CDS_LOG_PREFIX:
>>>>>
>>>>> 5) DumpSymbolAndStringTable.java
>>>>>
>>>>> 37     private static final String my_string = 
>>>>> "DumpSymbolAndStringTable";
>>>>>
>>>>> Unused variable?
>>>>>
>>>>> thanks,
>>>>>
>>>>> Calvin
>>>>>
>>>>> On 8/11/20 10:36 AM, Yumin Qi wrote:
>>>>>> Forget to send to @core-lib-dev, the patch changed jdk code.
>>>>>>
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> Yumin
>>>>>>
>>>>>>
>>>>>>
>>>>>> -------- Forwarded Message --------
>>>>>> Subject:     RFR: 8247536: Support pre-generated MethodHandle 
>>>>>> lambda forms in CDS
>>>>>> Date:     Tue, 11 Aug 2020 07:44:34 -0700
>>>>>> From:     Yumin Qi <yumin.qi at oracle.com>
>>>>>> To:     hotspot-runtime-dev at openjdk.java.net
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hi, Please reivew
>>>>>>
>>>>>>   bug: https://bugs.openjdk.java.net/browse/JDK-8247536
>>>>>>   Webrev: http://cr.openjdk.java.net/~minqi/2020/8247536/webrev-01/
>>>>>>
>>>>>>   Summary: CDS does not archive pre-generated lambda form classes 
>>>>>> for method handles:
>>>>>>
>>>>>> [0.142s][info][class,load] 
>>>>>> java.lang.invoke.LambdaForm$MH/0x0000000800066c40 source: 
>>>>>> __JVM_LookupDefineClass__
>>>>>>
>>>>>> The method handle resolution if not found in the holder class, a 
>>>>>> class with the method will be generated and loaded as vm internal 
>>>>>> created class and not archived like above. Those class names are 
>>>>>> mangled as combination of the class name and the class instance 
>>>>>> address.
>>>>>>
>>>>>> In this patch, collect those method holder class names and their 
>>>>>> associated methods' signatures when user specify 
>>>>>> DumpLoadedClassList, and record them in the log file in a format 
>>>>>> similar to the output format from traced by 
>>>>>> -Djava.lang.invoke.MethodHandle.TRACE_RESOLVE=true, but here use 
>>>>>> another name for CDS: 
>>>>>> -Djava.lang.invoke.MethodHandle.CDS_TRACE_RESOLVE=true instead. 
>>>>>> The line prefix also changed from "[LF_RESOLVE]" to 
>>>>>> "@lambda-invoke-handle".  At dump time, regenerate the holder 
>>>>>> class with those methods and replace the existing holder class and 
>>>>>> archived it. At runtime, the resolution of the holder class which 
>>>>>> contains those methods are loaded from CDS archive so avoid 
>>>>>> regenerating them again. The patch reorganized the code for Jlink 
>>>>>> plugin, so the new added InvokerBytecodeGeneratorHelper can be 
>>>>>> shared both by JLink plugin and CDS code. Also change made to the 
>>>>>> mangled generated class name at static dump, the class name 
>>>>>> combining the class name and a sequentially ordered number instead 
>>>>>> of the class instance address, which looks like a random.
>>>>>>
>>>>>>
>>>>>> To use this feature, one can do the dump/run just like done for a 
>>>>>> static dump/run, so no extra steps required.
>>>>>>
>>>>>>   1) java -XX:DumpLoadedClassList=myclasslist JavaApp
>>>>>>
>>>>>>       DumpLoadedClassList will turn on 
>>>>>> -Djava.lang.invoke.MethodHandle.CDS_TRACE_RESOLVE=true
>>>>>>
>>>>>>   2) java -Xshare:dump -XX:SharedClassListFile=myclasslist 
>>>>>> -XX:SharedArchiveFile=my.jsa JavaApp
>>>>>>
>>>>>>   3) java -Xshare:on -XX:SharedArchiveFile=my.jsa JavaApp
>>>>>>
>>>>>>   The performance on javac HelloWorld.java (javac-benchmark), no 
>>>>>> patch vs patch:
>>>>>>
>>>>>>    1:   2689285002  2641821474 (-47463528)      ---- 391.720 
>>>>>> 382.990 ( -8.730)      ----
>>>>>>    2:   2687495085  2632969688 (-54525397)      ---- 391.030 
>>>>>> 381.480 ( -9.550)      -----
>>>>>>    3:   2694664066  2636523114 (-58140952)      ----- 390.610 
>>>>>> 382.550 ( -8.060)      ----
>>>>>>    4:   2686554164  2639355233 (-47198931)      ---- 390.700 
>>>>>> 383.390 ( -7.310)      ---
>>>>>>    5:   2691072338  2633016687 (-58055651)      ----- 388.990 
>>>>>> 382.360 ( -6.630)      ---
>>>>>>    6:   2684448174  2644191854 (-40256320)      --- 389.450 
>>>>>> 382.990 ( -6.460)      ---
>>>>>>    7:   2694921227  2630505090 (-64416137)      ----- 389.300 
>>>>>> 383.160 ( -6.140)      ---
>>>>>>    8:   2685209712  2639334320 (-45875392)      ---- 388.370 
>>>>>> 381.060 ( -7.310)      ---
>>>>>>    9:   2695885942  2640618655 (-55267287)      ---- 389.560 
>>>>>> 381.100 ( -8.460)      ----
>>>>>>   10:   2689162942  2635658943 (-53503999)      ---- 389.690 
>>>>>> 379.110 (-10.580)      -----
>>>>>> ============================================================
>>>>>>         2689866989  2637396210 (-52470778)      ---- 389.941 
>>>>>> 382.017 ( -7.924)      ----
>>>>>>
>>>>>> instr delta =    -52470778    -1.9507%
>>>>>>
>>>>>> time  delta =       -7.924 ms -2.0321%
>>>>>>
>>>>>>   It will show much more improvement if compare with the default 
>>>>>> archive:
>>>>>>
>>>>>>                  no patch                        patch
>>>>>>
>>>>>> instr         3,996,847,605        3,320,928,995
>>>>>>
>>>>>> time(s).     0.686835162          0.474933546
>>>>>>
>>>>>>
>>>>>>   Tests:
>>>>>>
>>>>>> 1)jtreg on jdk/tools and hotspot/runtime local.
>>>>>>
>>>>>> 2) mach5 ter1,2
>>>>>>
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> Yumin
>>>>>>
>>>>>>   `
>>>>
>>>


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