maxWarmingSearchers: SOLR-91

git-svn-id: https://svn.apache.org/repos/asf/incubator/solr/trunk@495753 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -42,6 +42,11 @@ New Features
     * PatternReplaceFilter - applies a Pattern to each token in the
       stream, replacing match occurances with a specified replacement.
     (hossman)
+ 3. SOLR-91: allow configuration of a limit of the number of searchers 
+    that can be warming in the background.  This can be used to avoid
+    out-of-memory errors, or contention caused by more and more searchers
+    warming in the background.  An error is thrown if the limit specified
+    by maxWarmingSearchers in solrconfig.xml is exceeded. (yonik)
 
 Changes in runtime behavior
  1. Highlighting using DisMax will only pick up terms from the main 

example/solr/conf/solrconfig.xml

@@ -215,6 +215,11 @@
          warming. -->
     <useColdSearcher>false</useColdSearcher>
 
+    <!-- Maximum number of searchers that may be warming in the background
+      concurrently.  An error is returned if this limit is exceeded. Recommend
+      1-2 for read-only slaves, higher for masters w/o cache warming. -->
+    <maxWarmingSearchers>4</maxWarmingSearchers>
+
   </query>
 
 

src/java/org/apache/solr/core/SolrCore.java

@@ -182,7 +182,7 @@ public final class SolrCore {
       core = this;   // set singleton
 
       if (dataDir ==null) {
-        dataDir =SolrConfig.config.get("dataDir",Config.getInstanceDir()+"data");
+        dataDir = SolrConfig.config.get("dataDir",Config.getInstanceDir()+"data");
       }
 
       log.info("Opening new SolrCore at " + Config.getInstanceDir() + ", dataDir="+dataDir);
@@ -195,6 +195,8 @@ public final class SolrCore {
       this.dataDir = dataDir;
       this.index_path = dataDir + "/" + "index";
 
+      this.maxWarmingSearchers = SolrConfig.config.getInt("query/maxWarmingSearchers",Integer.MAX_VALUE);
+
       parseListeners();
 
       initIndex();
@@ -252,6 +254,7 @@ public final class SolrCore {
   final ExecutorService searcherExecutor = Executors.newSingleThreadExecutor();
   private int onDeckSearchers;  // number of searchers preparing
   private Object searcherLock = new Object();  // the sync object for the searcher
+  private final int maxWarmingSearchers;  // max number of on-deck searchers allowed
 
 
   public RefCounted<SolrIndexSearcher> getSearcher() {
@@ -337,20 +340,25 @@ public final class SolrCore {
       // first: increment count to signal other threads that we are
       //        opening a new searcher.
       onDeckSearchers++;
+      if (onDeckSearchers < 1) {
+        // should never happen... just a sanity check
+        log.severe("ERROR!!! onDeckSearchers is " + onDeckSearchers);
+        onDeckSearchers=1;  // reset
+      } else if (onDeckSearchers > maxWarmingSearchers) {
+        onDeckSearchers--;
+        String msg="Error opening new searcher. exceeded limit of maxWarmingSearchers="+maxWarmingSearchers + ", try again later.";
+        log.warning(msg);
+        // HTTP 503==service unavailable, or 409==Conflict
+        throw new SolrException(503,msg,true);
+      } else if (onDeckSearchers > 1) {
+        log.info("PERFORMANCE WARNING: Overlapping onDeckSearchers=" + onDeckSearchers);
+      }
     }
 
     // open the index synchronously
     // if this fails, we need to decrement onDeckSearchers again.
     SolrIndexSearcher tmp;
     try {
-      if (onDeckSearchers < 1) {
-        // should never happen... just a sanity check
-        log.severe("ERROR!!! onDeckSearchers is " + onDeckSearchers);
-        // reset to 1 (don't bother synchronizing)
-        onDeckSearchers=1;
-      } else if (onDeckSearchers > 1) {
-        log.info("PERFORMANCE WARNING: Overlapping onDeckSearchers=" + onDeckSearchers);
-      }
       tmp = new SolrIndexSearcher(schema, "main", index_path, true);
     } catch (Throwable th) {
       synchronized(searcherLock) {