pubsub: add default flow control

pongad · pongad · commit 6f38e883b357 · 2017-05-11T17:31:48.000+10:00
Fixes #2030.
diff --git a/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java b/google-cloud-pubsub/src/main/java/com/google/cloud/pubsub/spi/v1/Subscriber.java
@@ -458,7 +458,10 @@ public static final class Builder {
     Duration ackExpirationPadding = DEFAULT_ACK_EXPIRATION_PADDING;
     Duration maxAckExtensionPeriod = DEFAULT_MAX_ACK_EXTENSION_PERIOD;
 
-    FlowControlSettings flowControlSettings = FlowControlSettings.getDefaultInstance();
+    FlowControlSettings flowControlSettings =
+        FlowControlSettings.newBuilder()
+            .setMaxOutstandingRequestBytes(Runtime.getRuntime().maxMemory() / 5)
+            .build();
 
     ExecutorProvider executorProvider = DEFAULT_EXECUTOR_PROVIDER;
     @Nullable ExecutorProvider alarmsExecutorProvider;
