BEP: make stdout/stderr buffering configurable

For different applications, different size of buffered stdout/stderr might be
acceptable; essentially it is a trade off between latency and number of messages
generated. Put this trade off into the control of the user by adding an appropriate
flag.

Change-Id: I8fb4d19a336205fa28d01340f2f0b2be9b4a24f3
PiperOrigin-RevId: 181570242

2 files changed, 16 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
index 22efe8e79d..3998c36b9a 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceModule.java
@@ -91,9 +91,11 @@ public abstract class BuildEventServiceModule<T extends BuildEventServiceOptions
     if (streamer != null) {
       commandEnvironment.getReporter().addHandler(streamer);
       commandEnvironment.getEventBus().register(streamer);
+      long bufferSize =
+          commandEnvironment.getOptions().getOptions(optionsClass()).besOuterrBufferSize;
 
-      final SynchronizedOutputStream out = new SynchronizedOutputStream();
-      final SynchronizedOutputStream err = new SynchronizedOutputStream();
+      final SynchronizedOutputStream out = new SynchronizedOutputStream(bufferSize);
+      final SynchronizedOutputStream err = new SynchronizedOutputStream(bufferSize);
       this.outErr = OutErr.create(out, err);
       streamer.registerOutErrProvider(
           new BuildEventStreamer.OutErrProvider() {
diff --git a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceOptions.java b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceOptions.java
index fda0ac936c..0d1adae243 100644
--- a/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/buildeventservice/BuildEventServiceOptions.java
@@ -92,4 +92,16 @@ public class BuildEventServiceOptions extends OptionsBase {
             + "Defaults to none."
   )
   public List<String> besKeywords;
+
+  @Option(
+    name = "bes_outerr_buffer_size",
+    defaultValue = "10240",
+    documentationCategory = OptionDocumentationCategory.LOGGING,
+    effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
+    help =
+        "Specifies the maximal size of stdout or stderr to be buffered in BEP, before it is "
+            + "reported as a progress event. Individual writes are still reported in a single "
+            + "event, even if larger than the specified value."
+  )
+  public long besOuterrBufferSize;
 }