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https://issues.apache.org/jira/browse/PDFBOX-1337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13292920#comment-13292920
]
Kevin Jackson commented on PDFBOX-1337:
---------------------------------------
A simpler fix is to use ConcurrentHashMap:
### Eclipse Workspace Patch 1.0
#P pdfbox
Index: pdfbox/src/main/java/org/apache/pdfbox/util/PDFOperator.java
===================================================================
--- pdfbox/src/main/java/org/apache/pdfbox/util/PDFOperator.java
(revision 1324793)
+++ pdfbox/src/main/java/org/apache/pdfbox/util/PDFOperator.java
(working copy)
@@ -16,9 +16,8 @@
*/
package org.apache.pdfbox.util;
-import java.util.Collections;
-import java.util.HashMap;
import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
/**
* This class represents an Operator in the content stream.
@@ -32,7 +31,7 @@
private byte[] imageData;
private ImageParameters imageParameters;
- private static Map operators = Collections.synchronizedMap( new HashMap()
);
+ private static Map<String, PDFOperator> operators = new
ConcurrentHashMap<String, PDFOperator>();
/**
* Constructor.
> Improve PDFOperator performance on multithreading environment
> -------------------------------------------------------------
>
> Key: PDFBOX-1337
> URL: https://issues.apache.org/jira/browse/PDFBOX-1337
> Project: PDFBox
> Issue Type: Bug
> Components: Parsing, Utilities
> Affects Versions: 1.6.0
> Reporter: Alexis
> Attachments: thread_dump_pdfbox_1.6.0_PDFOperator_BLOCKED.txt
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> With more than 6 threads, the API PDFOperator#getOperator(String operator) is
> still blocked :
> Sample with 48 threads :
> pool-1-thread-46" - Thread t@72
> java.lang.Thread.State: RUNNABLE
> at org.apache.pdfbox.util.PDFOperator.getOperator(PDFOperator.java:76)
> at
> org.apache.pdfbox.pdfparser.PDFStreamParser.parseNextToken(PDFStreamParser.java:441)
> at
> org.apache.pdfbox.pdfparser.PDFStreamParser.access$000(PDFStreamParser.java:46)
> at
> org.apache.pdfbox.pdfparser.PDFStreamParser$1.tryNext(PDFStreamParser.java:175)
> at
> org.apache.pdfbox.pdfparser.PDFStreamParser$1.hasNext(PDFStreamParser.java:187)
> at
> org.apache.pdfbox.util.PDFStreamEngine.processSubStream(PDFStreamEngine.java:266)
> I propose to remove the synchronization of the attribute "operators" and set
> up a synchronization
> on the put operation. (This optimization saves 30 percent of time)
> public class PDFOperator
> {
> [...]
> // private static Map operators = Collections.synchronizedMap( new
> HashMap() );
> private static Map operators = new HashMap();
> [...]
> public static PDFOperator getOperator( String operator )
> {
> PDFOperator operation = null;
> if( operator.equals( "ID" ) || operator.equals( "BI" ) )
> {
> //we can't cache the ID operators.
> operation = new PDFOperator( operator );
> }
> else
> {
> operation = (PDFOperator)operators.get(operator);
> if( operation == null )
> {
> synchronized (operators) {
> operation = (PDFOperator)operators.get(operator);
> if ( operation == null ) {
> operation = new PDFOperator( operator );
> operators.put( operator, operation );
> }
> }
> }
> }
> return operation;
> }
> [...]
> }
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