Patch: Integrate async-profiler

[Jason Zaugg]

On Tue, 4 Aug 2020 at 14:40, Aleksey Shipilev <shade at redhat.com> wrote:
>
> On 8/4/20 1:42 AM, Jason Zaugg wrote:
> >> If you are fine with it, I can push the entire thing at once.
> >
> > Yes please.
>
> Pushed:
>   http://hg.openjdk.java.net/code-tools/jmh/rev/50b5cdf9c528

I found two minor issues in my patch.

AsyncProfiler.filterThread0 is not bound to the native implementation because I
neglected to include the native method declaration for getSamples and
the bulk JVMTI operation,
RegisterNatives, bails out after the first missing method.

I also realised that I incorrectly documented the filterThread API.
null represents the
current thread, not a wildcard for all threads.

diff --git a/jmh-core/src/main/java/org/openjdk/jmh/profile/AsyncProfiler.java
b/jmh-core/src/main/java/org/openjdk/jmh/profile/AsyncProfiler.java
index 66f572a8..e991207e 100644
--- a/jmh-core/src/main/java/org/openjdk/jmh/profile/AsyncProfiler.java
+++ b/jmh-core/src/main/java/org/openjdk/jmh/profile/AsyncProfiler.java
@@ -488,12 +488,11 @@ public final class AsyncProfiler implements
ExternalProfiler, InternalProfiler {
          * Enable or disable profile collection for threads.
          *
          * @param thread The thread to enable or disable.
-         *               <code>null</code> is a wildcard.
+         *               <code>null</code> indicates the current thread.
          * @param enable Whether to enable or disable.
          */
         public void filterThread(Thread thread, boolean enable) {
             if (thread == null) {
-                // All threads.
                 filterThread0(null, enable);
             } else {
                 synchronized (thread) {
@@ -512,6 +511,8 @@ public final class AsyncProfiler implements
ExternalProfiler, InternalProfiler {

         private native String execute0(String command) throws
IllegalArgumentException, IOException;

+        private native long getSamples();
+
         private native void filterThread0(Thread thread, boolean enable);
     }
 }

I have also proposed a change [1] to the native method registration in
async-profiler
that would avoid the tight coupling.

-jason

[1] https://github.com/jvm-profiling-tools/async-profiler/pull/337