8u60 backport RFR (M) 8067662: "java.lang.NullPointerException: Method name is null" from StackTraceElement.<init>
serguei.spitsyn at oracle.com
serguei.spitsyn at oracle.com
Wed Apr 8 18:38:21 UTC 2015
Thanks, Dan!
I will correct the grammar before the push..
Thanks,
Serguei
On 4/8/15 6:54 AM, Daniel D. Daugherty wrote:
> On 4/7/15 7:09 PM, serguei.spitsyn at oracle.com wrote:
>> On 4/7/15 6:07 PM, serguei.spitsyn at oracle.com wrote:
>>>
>>>
>>> On 4/7/15 2:01 PM, serguei.spitsyn at oracle.com wrote:
>>>> On 4/7/15 11:20 AM, Coleen Phillimore wrote:
>>>>>
>>>>> шI see. The PreviousVersionWalker is gone in 9 and you're using
>>>>> it to find the method.
>>>>>
>>>>> But this is only going to find the method if it happens to be in
>>>>> the cpCache somewhere. I think
>>>>> pv_node->prev_constant_pool()->pool_holder() is scratch_class (not
>>>>> 100% sure). In which case, you can look at that class to find the
>>>>> method with idnum.
>>>> I'm not 100% sure either.
>>>> Ok, I will check if using the prev_constant_pool()->pool_holder()
>>>> is going to work.
>>>> It'd make it more consistent with the jdk 9 fix.
>>>
>>> This is the updated webrev.
>> Sorry, forgot to paste the link:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8067662-JVMTI-trace.8u60.2/
>
> Comparing the two patch files looks good. A couple of nits:
>
> src/share/vm/classfile/javaClasses.cpp
> L1451: // Use specific ik version...
> L1884: // Use specific ik version...
> grammar: 'Use a specific ik version...'
>
> L1452: // refer to version that...
> L1885: // refer to version that...
> grammar: 'refer to a version that...'
>
> src/share/vm/classfile/javaClasses.hpp
> No comments.
>
> src/share/vm/oops/instanceKlass.cpp
> No comments.
>
> src/share/vm/oops/instanceKlass.hpp
> No comments.
>
> Thumbs up.
>
> Dan
>
>
>>
>> Thanks,
>> Serguei
>>
>>> It is more consistent with the jdk 9 fix.
>>> Thank you for the suggestion!
>>>
>>> Thanks,
>>> Serguei
>>>
>>>>
>>>> Important part is that at least the saved cpref can be used to find
>>>> method name in the
>>>> the_class cpool if the attempt to find in the previous list
>>>> cpCaches was unsuccessful.
>>>>
>>>> Thanks,
>>>> Serguei
>>>>
>>>>>
>>>>> Coleen
>>>>>
>>>>> On 4/7/15, 1:09 AM, serguei.spitsyn at oracle.com wrote:
>>>>>> Coleen,
>>>>>>
>>>>>> Thank you for looking at this!
>>>>>>
>>>>>> The main difference is in instanceKlass.cpp and instanceKlass.hpp.
>>>>>>
>>>>>> 8u60:
>>>>>> +Method* InstanceKlass::method_with_orig_idnum(int idnum) {
>>>>>> + if (idnum >= methods()->length()) {
>>>>>> + return NULL;
>>>>>> + }
>>>>>> + Method* m = methods()->at(idnum);
>>>>>> + if (m != NULL && m->orig_method_idnum() == idnum) {
>>>>>> + return m;
>>>>>> + }
>>>>>> + // Obsolete method idnum does not match the original idnum
>>>>>> + for (int index = 0; index < methods()->length(); ++index) {
>>>>>> + m = methods()->at(index);
>>>>>> + if (m->orig_method_idnum() == idnum) {
>>>>>> + return m;
>>>>>> + }
>>>>>> + }
>>>>>> + // None found, return null for the caller to handle.
>>>>>> + return NULL;
>>>>>> +}
>>>>>> +
>>>>>> +
>>>>>> +Method* InstanceKlass::method_with_orig_idnum(int idnum, int version) {
>>>>>> + if (constants()->version() == version) {
>>>>>> + return method_with_orig_idnum(idnum);
>>>>>> + }
>>>>>> + ConstantPoolCache* cp_cache = NULL;
>>>>>> + PreviousVersionWalker pvw(Thread::current(), (InstanceKlass*)this);
>>>>>> + for (PreviousVersionNode * pv_node = pvw.next_previous_version();
>>>>>> + pv_node != NULL; pv_node = pvw.next_previous_version()) {
>>>>>> + ConstantPool* prev_cp = pv_node->prev_constant_pool();
>>>>>> + if (prev_cp->version() == version) {
>>>>>> + cp_cache = prev_cp->cache();
>>>>>> + break;
>>>>>> + }
>>>>>> + }
>>>>>> + if (cp_cache == NULL) {
>>>>>> + return NULL; // The pv_node is gone, no method is found
>>>>>> + }
>>>>>> + Method* method = NULL;
>>>>>> + for (int i = 0; i < cp_cache->length(); i++) {
>>>>>> + ConstantPoolCacheEntry* entry = cp_cache->entry_at(i);
>>>>>> + method = entry->get_interesting_method_entry(this);
>>>>>> + if (method == NULL) {
>>>>>> + continue; // skip uninteresting entries
>>>>>> + }
>>>>>> + if (method->orig_method_idnum() == idnum) {
>>>>>> + return method;
>>>>>> + }
>>>>>> + }
>>>>>> + // None found, return null for the caller to handle.
>>>>>> + return NULL;
>>>>>> +}
>>>>>>
>>>>>>
>>>>>> jdk 9:
>>>>>>
>>>>>> +Method* InstanceKlass::method_with_orig_idnum(int idnum) {
>>>>>> + if (idnum >= methods()->length()) {
>>>>>> + return NULL;
>>>>>> + }
>>>>>> + Method* m = methods()->at(idnum);
>>>>>> + if (m != NULL && m->orig_method_idnum() == idnum) {
>>>>>> + return m;
>>>>>> + }
>>>>>> + // Obsolete method idnum does not match the original idnum
>>>>>> + for (int index = 0; index < methods()->length(); ++index) {
>>>>>> + m = methods()->at(index);
>>>>>> + if (m->orig_method_idnum() == idnum) {
>>>>>> + return m;
>>>>>> + }
>>>>>> + }
>>>>>> + // None found, return null for the caller to handle.
>>>>>> + return NULL;
>>>>>> +}
>>>>>> +
>>>>>> +
>>>>>> +Method* InstanceKlass::method_with_orig_idnum(int idnum, int version) {
>>>>>> + InstanceKlass* holder = get_klass_version(version);
>>>>>> + if (holder == NULL) {
>>>>>> + return NULL; // The version of klass is gone, no method is found
>>>>>> + }
>>>>>> + Method* method = holder->method_with_orig_idnum(idnum);
>>>>>> + return method;
>>>>>> +}
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Serguei
>>>>>>
>>>>>>
>>>>>> On 4/6/15 6:49 PM, Coleen Phillimore wrote:
>>>>>>>
>>>>>>> This backport looks good. Why didn't the patch apply cleanly?
>>>>>>> It seems mostly the same to me.
>>>>>>> Thanks,
>>>>>>> Coleen
>>>>>>>
>>>>>>> On 4/6/15, 7:50 PM, serguei.spitsyn at oracle.com wrote:
>>>>>>>> Coleen and Dan,
>>>>>>>>
>>>>>>>> I'm asking you as the jdk 9 reviewers...
>>>>>>>>
>>>>>>>> Please, let me know if you have any chance and plans to review
>>>>>>>> this.
>>>>>>>> Would it be enough to have just one (R) reviewer for a
>>>>>>>> non-clean backport?
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Serguei
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 4/2/15 5:03 PM, serguei.spitsyn at oracle.com wrote:
>>>>>>>>> Please, review the jdk 8u60 backport for:
>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8067662
>>>>>>>>>
>>>>>>>>> 8u60 hotspot webrev:
>>>>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8067662-JVMTI-trace.8u60
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 8u60 webrev for unit test update (the fix applies cleanly):
>>>>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8067662-JVMTI-trace-test.8u60
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 9 hotspot webrev:
>>>>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8067662-JVMTI-trace.2
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 9 webrev for unit test update:
>>>>>>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8067662-JVMTI-trace-test.2
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Summary:
>>>>>>>>> The 9 fix can not be applied cleanly so that I have to
>>>>>>>>> rework the fix a little bit.
>>>>>>>>>
>>>>>>>>> An NPE is trown in a thread dumping via JMX when doing CPU
>>>>>>>>> profiling in NetBeans Profiler and VisualVM.
>>>>>>>>> The issue is that the methods and related klass versions are
>>>>>>>>> not kept alive if a class redefinition
>>>>>>>>> takes place between catching a Throwable and taking a thread
>>>>>>>>> dump.
>>>>>>>>> It can result in loosing an obsolete method, and so, the
>>>>>>>>> reconstruction of method name becomes impossible.
>>>>>>>>> In such a case, the null reference is returned instead of a
>>>>>>>>> valid method name.
>>>>>>>>>
>>>>>>>>> The solution is to use current klass version and method
>>>>>>>>> orig_idnum instead of ordinary method idnum
>>>>>>>>> to find required method pointer. In the worst case when the
>>>>>>>>> related klass version is gone
>>>>>>>>> (was not included to or was removed from the
>>>>>>>>> previous_versions linked list), a saved method name
>>>>>>>>> CP index of the latest klass version can be used to restore
>>>>>>>>> the method name.
>>>>>>>>> The footprint extra overhead for this approach is u2 per
>>>>>>>>> stack frame.
>>>>>>>>>
>>>>>>>>> Testing in progress:
>>>>>>>>> In progress: nsk redefine classes tests, JTREG
>>>>>>>>> java/lang/instrument
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Serguei
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/serviceability-dev/attachments/20150408/fecdb261/attachment-0001.html>
More information about the serviceability-dev
mailing list