[HIVE-10081] LLAP: Make the low-level IO threadpool configurable

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Assignee: Prasanth Jayachandran Assign to me
• Reporter: Gopal Vijayaraghavan
• Created: 25/Mar/15 07:12
• Updated: 01/Apr/15 06:20
• Resolved: 01/Apr/15 05:19

Description

The LLAP low level reader thread-pool is hard-limited to 10-threads, which is not sufficient to max out the network bandwidth on a 10GigE network.

These threads are often seen in IOWAIT, since they are reading remote data.

A dumb fix for my 12-core instance was to use a higher thread-pool count for the IO read-ahead.

diff --git a/llap-server/src/java/org/apache/hadoop/hive/llap/io/api/impl/LlapIoImpl.java b/llap-server/src/java/org/apache/hadoop/hive/llap/io/api/impl/LlapIoImpl.java
index 3f9ddfb..b7cd177 100644
--- a/llap-server/src/java/org/apache/hadoop/hive/llap/io/api/impl/LlapIoImpl.java
+++ b/llap-server/src/java/org/apache/hadoop/hive/llap/io/api/impl/LlapIoImpl.java
@@ -105,7 +105,7 @@ private LlapIoImpl(Configuration conf) throws IOException {
       cachePolicy.setEvictionListener(metadataCache);
     }
     // Arbitrary thread pool. Listening is used for unhandled errors for now (TODO: remove?)
-    executor = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(10));
+    executor = MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(24));

Issue Links

• relates to: HIVE-9850 documentation for llap