Consuming stack traces noticeably slower in Java 11 than Java 8

Question

I was comparing the performance of JDK 8 and 11 using jmh 1.21 when I ran across some surprising numbers:

Java versi         


        

Answer 1

I suspect this is due to several changes.

8->9 regression happened while switching to StackWalker for generating the stack traces (JDK-8150778). Unfortunately, this made VM native code intern a lot of strings, and StringTable becomes the bottleneck. If you profile OP's benchmark, you will see the profile like in JDK-8151751. It should be enough to perf record -g the entire JVM that runs the benchmark, and then look into perf report. (Hint, hint, you can do it yourself next time!)

And 10->11 regression must have happened later. I suspect this is due to StringTable preparations for switching to fully concurrent hash table (JDK-8195100, which, as Claes points out, is not entirely in 11) or something else (class data sharing changes?).

Either way, interning on fast path is a bad idea, and patch for JDK-8151751 should have dealt with both regressions.

Watch this:

8u191: 15108 ± 99 ns/op [so far so good]

-   54.55%     0.37%  java     libjvm.so           [.] JVM_GetStackTraceElement 
   - 54.18% JVM_GetStackTraceElement                          
      - 52.22% java_lang_Throwable::get_stack_trace_element   
         - 48.23% java_lang_StackTraceElement::create         
            - 17.82% StringTable::intern                      
            - 13.92% StringTable::intern                      
            - 4.83% Klass::external_name                      
            + 3.41% Method::line_number_from_bci              

"head": 22382 ± 134 ns/op [regression]

-   69.79%     0.05%  org.sample.MyBe  libjvm.so  [.] JVM_InitStackTraceElement
   - 69.73% JVM_InitStackTraceElementArray                    
      - 69.14% java_lang_Throwable::get_stack_trace_elements  
         - 66.86% java_lang_StackTraceElement::fill_in        
            - 38.48% StringTable::intern                      
            - 21.81% StringTable::intern                      
            - 2.21% Klass::external_name                      
              1.82% Method::line_number_from_bci              
              0.97% AccessInternal::PostRuntimeDispatch

"head" + JDK-8151751 patch: 7511 ± 26 ns/op [woot, even better than 8u]

-   22.53%     0.12%  org.sample.MyBe  libjvm.so  [.] JVM_InitStackTraceElement
   - 22.40% JVM_InitStackTraceElementArray                    
      - 20.25% java_lang_Throwable::get_stack_trace_elements  
         - 12.69% java_lang_StackTraceElement::fill_in        
            + 6.86% Method::line_number_from_bci              
              2.08% AccessInternal::PostRuntimeDispatch