store checkpoint repeatidly writes the same checkpoint record - results in
unnecessary writes
---------------------------------------------------------------------------------------------
Key: AMQ-1798
URL: https://issues.apache.org/activemq/browse/AMQ-1798
Project: ActiveMQ
Issue Type: Improvement
Components: Message Store
Affects Versions: 5.1.0
Environment: all - default config
Reporter: Gary Tully
Priority: Minor
I left a simple test running over night to find that the data file index was
incrementing, it turns out that the checkpoint functionality does not remember
its last mark and will always write a mark, even if it is the same as the last
written mark, with a small dataFileSize I found that the current data file
index was not as expected.
This is really just odd behaviour rather than bug as I don't think it has any
really adverse effects unless there is a cap on the file id. (which there is
not!)
the following change ensures that checkpoint will only write a record if there
is a change to the last recorded mark.
Index: src/main/java/org/apache/activemq/store/amq/AMQPersistenceAdapter.java
===================================================================
--- src/main/java/org/apache/activemq/store/amq/AMQPersistenceAdapter.java
(revision 667120)
+++ src/main/java/org/apache/activemq/store/amq/AMQPersistenceAdapter.java
(working copy)
@@ -375,12 +375,13 @@
LOG.debug("Checkpoint started.");
}
- Location newMark = null;
+ Location currentMark = asyncDataManager.getMark();
+ Location newMark = currentMark;
Iterator<AMQMessageStore> queueIterator =
queues.values().iterator();
while (queueIterator.hasNext()) {
final AMQMessageStore ms = queueIterator.next();
Location mark = (Location)ms.getMark();
- if (mark != null && (newMark == null ||
newMark.compareTo(mark) < 0)) {
+ if (mark != null && mark.compareTo(newMark) > 0) {
newMark = mark;
}
}
@@ -388,12 +389,12 @@
while (topicIterator.hasNext()) {
final AMQTopicMessageStore ms = topicIterator.next();
Location mark = (Location)ms.getMark();
- if (mark != null && (newMark == null ||
newMark.compareTo(mark) < 0)) {
+ if (mark != null && mark.compareTo(newMark) > 0) {
newMark = mark;
}
}
try {
- if (newMark != null) {
+ if (newMark != currentMark) {
if (LOG.isDebugEnabled()) {
LOG.debug("Marking journal at: " + newMark);
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