Harden Profiler slow tasks capping test

Internally slow task aggregators are sharded by thread id, so we need to throw
some threads at it to get an interesting test case, otherwise everything comes
from one thread and lands in one shard and the shard combination logic isn't
exercised. Of course it's possible that all the threads created in the test
wind up landing in the same shard, let's just pretend that's not going to
happen, since the odds are pretty low.

PiperOrigin-RevId: 195141874

1 files changed, 50 insertions, 5 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/profiler/ProfilerTest.java b/src/test/java/com/google/devtools/build/lib/profiler/ProfilerTest.java
index a3e7993481..5840294c59 100644
--- a/src/test/java/com/google/devtools/build/lib/profiler/ProfilerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/profiler/ProfilerTest.java
@@ -28,6 +28,7 @@ import com.google.devtools.build.lib.testutil.FoundationTestCase;
 import com.google.devtools.build.lib.testutil.ManualClock;
 import com.google.devtools.build.lib.testutil.Suite;
 import com.google.devtools.build.lib.testutil.TestSpec;
+import com.google.devtools.build.lib.testutil.TestUtils;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import java.io.InputStream;
@@ -215,16 +216,60 @@ public class ProfilerTest extends FoundationTestCase {
         BlazeClock.instance(),
         BlazeClock.instance().nanoTime());
 
+    // Add some fast tasks - these shouldn't show up in the slowest.
+    for (int i = 0; i < ProfilerTask.VFS_STAT.slowestInstancesCount; i++) {
+      profiler.logSimpleTask(
+          /*startTimeNanos=*/ 1,
+          /*stopTimeNanos=*/ ProfilerTask.VFS_STAT.minDuration + 10,
+          ProfilerTask.VFS_STAT,
+          "stat");
+    }
+
+    // Add some slow tasks we expect to show up in the slowest.
     List<Long> expectedSlowestDurations = new ArrayList<>();
     for (int i = 0; i < ProfilerTask.VFS_STAT.slowestInstancesCount; i++) {
-      long fakeDuration = i + 1000;
-      profiler.logSimpleTask(1, fakeDuration + 1, ProfilerTask.VFS_STAT, "stat");
+      long fakeDuration = ProfilerTask.VFS_STAT.minDuration + i + 10_000;
+      profiler.logSimpleTask(
+          /*startTimeNanos=*/ 1,
+          /*stopTimeNanos=*/ fakeDuration + 1,
+          ProfilerTask.VFS_STAT,
+          "stat");
       expectedSlowestDurations.add(fakeDuration);
     }
 
-    // Sprinkle in a whole bunch of fast tasks.
-    for (int i = 0; i < 100; i++) {
-      profiler.logSimpleTask(1, i + 1, ProfilerTask.VFS_STAT, "stat" + i);
+    // Sprinkle in a whole bunch of fast tasks from different thread ids - necessary because
+    // internally aggregation is sharded across several aggregators, sharded by thread id.
+    // It's possible all these threads wind up in the same shard, we'll take our chances.
+    ImmutableList.Builder<Thread> threadsBuilder = ImmutableList.builder();
+    try {
+      for (int i = 0; i < 32; i++) {
+        Thread thread = new Thread() {
+          @Override
+          public void run() {
+            for (int j = 0; j < 100; j++) {
+              profiler.logSimpleTask(
+                  /*startTimeNanos=*/ 1,
+                  /*stopTimeNanos=*/ ProfilerTask.VFS_STAT.minDuration + j + 1,
+                  ProfilerTask.VFS_STAT,
+                  "stat");
+            }
+          }
+        };
+        threadsBuilder.add(thread);
+        thread.start();
+      }
+    } finally {
+      threadsBuilder.build().forEach(
+          t -> {
+            try {
+              t.join(TestUtils.WAIT_TIMEOUT_MILLISECONDS);
+            } catch (InterruptedException e) {
+              t.interrupt();
+              // This'll go ahead and interrupt all the others. The thread we just interrupted is
+              // lightweight enough that it's reasonable to assume it'll exit.
+              Thread.currentThread().interrupt();
+            }
+          });
     }
 
     ImmutableList<SlowTask> slowTasks = ImmutableList.copyOf(profiler.getSlowestTasks());