RFR: 8247536: Support for pre-generated java.lang.invoke classes in CDS static archive
Ioi Lam
ioi.lam at oracle.com
Sun Aug 16 01:27:38 UTC 2020
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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