From b528ca81f5de8c7dc8a09584079c140a6d3182f7 Mon Sep 17 00:00:00 2001
From: Fabian Meumertzheim <fabian@meumertzhe.im>
Date: Fri, 31 Oct 2025 14:06:11 +0100
Subject: [PATCH] Improve logging for dynamic execution crashes

---
 .../lib/dynamic/DynamicSpawnStrategy.java     | 20 +++++++++++--------
 .../remote/merkletree/MerkleTreeComputer.java |  6 +++++-
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/src/main/java/com/google/devtools/build/lib/dynamic/DynamicSpawnStrategy.java b/src/main/java/com/google/devtools/build/lib/dynamic/DynamicSpawnStrategy.java
index 9b0bd0d7e8bf4c..64faf1106f333b 100644
--- a/src/main/java/com/google/devtools/build/lib/dynamic/DynamicSpawnStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/dynamic/DynamicSpawnStrategy.java
@@ -606,14 +606,18 @@ private static ImmutableList<SpawnResult> waitBranch(
         // for cancellation. Assume the latter here because if this was actually a user interrupt,
         // our own get() would have been interrupted as well. It makes no sense to propagate the
         // interrupt status across threads.
-        context
-            .getEventHandler()
-            .handle(
-                Event.info(
-                    String.format(
-                        "Caught InterruptedException from ExecutionException for %s branch of %s,"
-                            + " which may cause a crash.",
-                        mode, getSpawnReadableId(branch.getSpawn()))));
+        if (options.debugSpawnScheduler) {
+          context
+              .getEventHandler()
+              .handle(
+                  Event.info(
+                      String.format(
+                          "Caught InterruptedException from ExecutionException for %s branch of %s,"
+                              + " which may cause a crash:\n%s",
+                          mode,
+                          getSpawnReadableId(branch.getSpawn()),
+                          Throwables.getStackTraceAsString(cause))));
+        }
         return null;
       } else {
         // Even though we cannot enforce this in the future's signature (but we do in Branch#call),
diff --git a/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTreeComputer.java b/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTreeComputer.java
index f74a1c950235b7..1b3d14e72a08cf 100644
--- a/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTreeComputer.java
+++ b/src/main/java/com/google/devtools/build/lib/remote/merkletree/MerkleTreeComputer.java
@@ -950,7 +950,11 @@ private static <T> T getFromFuture(Future<T> future) throws IOException, Interru
       future.cancel(/* mayInterruptIfRunning= */ true);
       throw e;
     } catch (CancellationException e) {
-      throw new InterruptedException();
+      // TODO(b/173153395): Drop the cause when the crashes with dynamic execution have been
+      // diagnosed.
+      var interruptedException = new InterruptedException();
+      interruptedException.initCause(e);
+      throw interruptedException;
     } catch (ExecutionException e) {
       if (e.getCause() instanceof WrappedException wrappedException) {
         wrappedException.unwrapAndThrow();