[GitHub] [incubator-druid] xvrl commented on a change in pull request #7606: Set direct memory if unable to detect JVM config

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xvrl commented on a change in pull request #7606: Set direct memory if unable to detect JVM config
URL: https://github.com/apache/incubator-druid/pull/7606#discussion_r282309638
 
 

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 File path: processing/src/main/java/org/apache/druid/query/DruidProcessingConfig.java
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 @@ -52,7 +52,22 @@ public int intermediateComputeSizeBytes()
       return computedBufferSizeBytes.get();
     }
 
-    long directSizeBytes = JvmUtils.getRuntimeInfo().getDirectMemorySizeBytes();
+    long directSizeBytes;
+    try {
+      directSizeBytes = JvmUtils.getRuntimeInfo().getDirectMemorySizeBytes();
 
 Review comment:
   yes, the call will always fail in Java 9 and above.
   
   DEFAULT_PROCESSING_BUFFER_SIZE_BYTES is -1, so this logic should only apply if they haven't configured anything and we need to auto-size the buffer.
   
   This only changes the auto-sizing logic to assume the maximum available direct memory is at least 25% of heap size, which should be relatively safe, given that JDKs now default to max direct memory = max heap size.
   
   The only reason I picked a fraction of it is to provide a better out of the box experience for someone kicking the tires, and avoid having their memory usage be twice as much as the heap size they configured, but I picked this number fairly arbitrarily, so I'd be happy to revisit if we think a different default is better.

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