From 0f5622df722ee695d06fb889df679291faa54f9d Mon Sep 17 00:00:00 2001
From: Michael Bayne <mdb@samskivert.com>
Date: Wed, 3 Oct 2018 08:47:19 -0700
Subject: [PATCH] Allow thread pool to be sized with -Dthread_pool_size.

Also use num processors minus one instead of num processors.
---
 .../main/java/com/threerings/getdown/data/Application.java  | 2 +-
 core/src/main/java/com/threerings/getdown/data/Digest.java  | 3 +--
 .../src/main/java/com/threerings/getdown/data/SysProps.java | 6 ++++++
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/com/threerings/getdown/data/Application.java b/core/src/main/java/com/threerings/getdown/data/Application.java
index 02a29d4..9bbb98b 100644
--- a/core/src/main/java/com/threerings/getdown/data/Application.java
+++ b/core/src/main/java/com/threerings/getdown/data/Application.java
@@ -1224,7 +1224,7 @@ public class Application
         // resources are verified on background threads supplied by the thread pool, and progress
         // is reported by posting runnable actions to the actions queue which is processed by the
         // main (UI) thread
-        Executor exec = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
+        Executor exec = Executors.newFixedThreadPool(SysProps.threadPoolSize());
         final BlockingQueue<Runnable> actions = new LinkedBlockingQueue<Runnable>();
         final int[] completed = new int[1];
 
diff --git a/core/src/main/java/com/threerings/getdown/data/Digest.java b/core/src/main/java/com/threerings/getdown/data/Digest.java
index 5fc924c..bd4a775 100644
--- a/core/src/main/java/com/threerings/getdown/data/Digest.java
+++ b/core/src/main/java/com/threerings/getdown/data/Digest.java
@@ -56,8 +56,7 @@ public class Digest
         throws IOException
     {
         // first compute the digests for all the resources in parallel
-        ExecutorService exec = Executors.newFixedThreadPool(
-            Runtime.getRuntime().availableProcessors());
+        ExecutorService exec = Executors.newFixedThreadPool(SysProps.threadPoolSize());
         final Map<Resource, String> digests = new ConcurrentHashMap<>();
         final BlockingQueue<Object> completed = new LinkedBlockingQueue<>();
         final int fversion = version;
diff --git a/core/src/main/java/com/threerings/getdown/data/SysProps.java b/core/src/main/java/com/threerings/getdown/data/SysProps.java
index 6da630e..ac1960e 100644
--- a/core/src/main/java/com/threerings/getdown/data/SysProps.java
+++ b/core/src/main/java/com/threerings/getdown/data/SysProps.java
@@ -107,6 +107,12 @@ public class SysProps
         return Integer.getInteger("read_timeout", 30);
     }
 
+    /** Returns the number of threads used to perform digesting and verifying operations in
+      * parallel. Usage: {@code -Dthread_pool_size=N} */
+    public static int threadPoolSize () {
+        return Integer.getInteger("thread_pool_size", Runtime.getRuntime().availableProcessors()-1);
+    }
+
     /** Parses a Java version system property using the supplied regular expression. The numbers
       * extracted from the regexp will be placed in each consecutive hundreds position in the
       * returned value.