Fix lock contention in Reporter.startTask/.finishTask by:

- Using a thread-safe container to store handlers.
- Using a ThreadLocal NumberFormat to produce readable action counts.
  NumberFormat (or rather the default implementation DecimalFormat) use
  internal state and locking.
- Adding a lock-free fast path for START and FINISH events in
  ExperimentalEventHandler.

RELNOTES: None.
PiperOrigin-RevId: 208479896

1 files changed, 10 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
index 49ba57ba1b..16caed049b 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/ExperimentalEventHandler.java
@@ -312,7 +312,16 @@ public class ExperimentalEventHandler implements EventHandler {
   }
 
   @Override
-  public synchronized void handle(Event event) {
+  public void handle(Event event) {
+    if (!debugAllEvents
+        && !showTimestamp
+        && (event.getKind() == EventKind.START || event.getKind() == EventKind.FINISH)) {
+      return;
+    }
+    handleLocked(event);
+  }
+
+  private synchronized void handleLocked(Event event) {
     try {
       if (debugAllEvents) {
         // Debugging only: show all events visible to the new UI.