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From build...@apache.org
Subject svn commit: r1028240 - in /websites/production/activemq/content: cache/main.pageCache kahadb.html
Date Wed, 11 Apr 2018 14:23:33 GMT
Author: buildbot
Date: Wed Apr 11 14:23:33 2018
New Revision: 1028240

Log:
Production update by buildbot for activemq

Modified:
    websites/production/activemq/content/cache/main.pageCache
    websites/production/activemq/content/kahadb.html

Modified: websites/production/activemq/content/cache/main.pageCache
==============================================================================
Binary files - no diff available.

Modified: websites/production/activemq/content/kahadb.html
==============================================================================
--- websites/production/activemq/content/kahadb.html (original)
+++ websites/production/activemq/content/kahadb.html Wed Apr 11 14:23:33 2018
@@ -87,7 +87,7 @@
     </persistenceAdapter>
  </broker>
 </pre>
-</div></div><h3 id="KahaDB-KahaDBProperties">KahaDB Properties</h3><div
class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1"
rowspan="1" class="confluenceTh"><p>Property</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Default</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Comments</p></th></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>archiveCorruptedIndex</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
corrupted indexes found at startup will be archived (not deleted).</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>archiveDataLogs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
will move a message data log to the archi
 ve directory instead of deleting it.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>checkForCorruptJournalFiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
will check for corrupt journal files on startup and try and recover them.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>checkpointInterval</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>5000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Time (ms) before check-pointing the
journal.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>checksumJournalFiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Create a checksum for a journal file.
The presence of a checksum is requi
 red in order for the persistence adapter to be able to detect corrupt journal files.</p><p>Before
<strong>ActiveMQ 5.9.0</strong>: the default is <strong><code>false</code></strong>.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>cleanupInterval</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>30000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The interval (in ms) between consecutive
checks that determine which journal files, if any, are eligible for removal from the message
store. An eligible journal file is one that has no outstanding references.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>compactAcksAfterNoGC</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
when the acknowledgement compaction feature is enabled this value controls how many store

 GC cycles must be completed with no other files being cleaned up before the compaction logic
is triggered to possibly compact older acknowledgements spread across journal files into a
new log file.&#160; The lower the value set the faster the compaction may occur which
can impact performance if it runs to often.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>compactAcksIgnoresStoreGrowth</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:&#160;when
the acknowledgement compaction feature is enabled this value controls whether compaction is
run when the store is still growing or if it should only occur when the store has stopped
growing (either due to idle or store limits reached).&#160; If enabled the compaction
runs regardless of the store still having room or being active which can decrease overall
performance but reclaim s
 pace faster.&#160;</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>concurrentStoreAndDispatchQueues</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Enable the dispatching of Queue messages
to interested clients to happen concurrently with message storage.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>concurrentStoreAndDispatchTopics</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Enable the dispatching of Topic messages
to interested clients to happen concurrently with message storage</p><div class="confluence-information-macro
confluence-information-macro-warning"><span class="aui-icon aui-icon-small aui-iconfont-error
confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>Enabling
this property is 
 not recommended.</p></div></div></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>directory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>activemq-data</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The path to the directory to use
to store the message store data and log files.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>directoryArchive</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>null</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Define the directory to move data
logs to when they all the messages they contain have been consumed.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>enableAckCompaction</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting controls whether t
 he store will perform periodic compaction of older journal log files that contain only Message
acknowledgements. By compacting these older acknowledgements into new journal log files the
older files can be removed freeing space and allowing the message store to continue to operate
without hitting store size limits.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>enableIndexWriteAsync</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
the index is updated asynchronously.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>enableJournalDiskSyncs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><span>Ensure every journal
write is followed by a disk sync (JMS durability requirement).</span></p><div
class="conflu
 ence-information-macro confluence-information-macro-warning"><span class="aui-icon
aui-icon-small aui-iconfont-error confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>This property is deprecated as of <strong>ActiveMQ</strong>
<strong>5.14.0</strong>.</p><p>From <strong>ActiveMQ</strong>
<strong>5.14.0</strong>: see <span style="color: rgb(34,34,34);"><strong><code>journalDiskSyncStrategy</code></strong>.</span></p></div></div></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>ignoreMissingJournalfiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
reports of missing journal files are ignored.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>indexCacheSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10000</code></p></td><td
colspan
 ="1" rowspan="1" class="confluenceTd"><p>Number of index pages cached in memory.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>indexDirectory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd">&#160;</td><td colspan="1" rowspan="1"
class="confluenceTd"><p><span>From <strong>ActiveMQ 5.10.0</strong>:
If set, configures where the KahaDB index files (<strong><code>db.data</code></strong>
and&#160;<strong><code>db.redo</code></strong>) will be stored.
If not set, the index files are stored in the directory specified by the&#160;<strong><code>directory</code></strong>
attribute.</span></p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>indexWriteBatchSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>1000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Number of indexes written in a batch.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code><span>journalD
 iskSyncInterval</span></code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>1000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Interval (ms) for when to perform
a disk sync when&#160;<strong><code>journalDiskSyncStrategy=periodic</code></strong>.
A sync will only be performed if a write has occurred to the journal since the last disk sync
or when the journal rolls over to a new journal file.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code><span>journalDiskSyncStrategy</span></code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>always</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting configures the disk sync policy. The list of available sync strategies are (in
order of decreasing safety, and increasing performance):</p><ul><li><p><strong><code>always</code></strong>
<span>Ensure every journal write is followed by a disk sync (JM
 S durability requirement). This is the safest option but is also the slowest because it requires
a sync after every message write. This is equivalent to the deprecated property&#160;<strong><code>enableJournalDiskSyncs=true</code></strong>.</span></p></li><li><p><strong><code>periodic</code></strong>
<span style="color: rgb(34,34,34);">The disk will be synced at set intervals (if a write
has occurred) instead of after every journal write which will reduce the load on the disk
and should improve throughput</span>. The disk will also be synced when rolling over
to a new journal file. The default interval is 1 second. The default interval offers very
good performance, whilst being safer than&#160;<strong><code>never</code></strong>
disk syncing, as data loss is limited to a maximum of 1 second's worth. See <strong><code>journalDiskSyncInterval</code></strong>
to change the frequency of disk syncs.</p></li><li><p><strong><code>never</code></strong>
A sync will never be explicitly called
  and it will be up to the operating system to flush to disk. This is equivalent to setting
the deprecated property <strong><code>enableJournalDiskSyncs=false</code></strong>.
This is the fastest option but is the least safe as there's no guarantee as to when data is
flushed to disk. Consequently message loss <em>can</em> occur on broker failure.</p></li></ul></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>journalMaxFileLength</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>32mb</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>A hint to set the maximum size of
the message data logs.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>maxAsyncJobs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The maximum number of asynchronous
messages that will be queued awaiting storage (should be the same as the
  number of concurrent MessageProducers).</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>preallocationScope</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>entire_journal</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting configures how journal data files are preallocated. The default strategy preallocates
the journal file on first use using the appender thread.&#160;</p><ul><li><p><strong><code>entire_journal_async</code></strong>
will use preallocate ahead of time in a separate thread.</p></li><li><p><strong><code>none</code></strong>
disables preallocation.</p></li></ul><p>On SSD, using&#160;<strong><code>entire_journal_async</code></strong>
avoids delaying writes pending preallocation on first use.</p><p><strong>Note</strong>:
on HDD the additional thread contention for disk has a negative impact. Therefore use the
default.</p></td></tr><tr><td colspan="1" rows
 pan="1" class="confluenceTd"><p><code>preallocationStrategy</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>sparse_file</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.12.0</strong>:&#160;This
setting configures how the broker will try to preallocate the journal files when a new journal
file is needed.</p><ul><li><p><strong><code>sparse_file</code></strong>
- sets the file length, but does not populate it with any data.</p></li><li><p><strong><code>os_kernel_copy</code></strong>
- delegates the preallocation to the Operating System.</p></li><li><p><strong><code>zeros</code></strong>&#160;
- each preallocated journal file contains nothing but <strong><code>0x00</code></strong>
throughout.</p></li></ul></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>storeOpenWireVersion</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>11</code></p></td><td
colspan="1" rowspan="1" class="
 confluenceTd"><p>Determines the version of OpenWire commands that are marshaled
to the KahaDB journal.&#160;</p><p>Before <strong>ActiveMQ 5.12.0</strong>:
the default value is <strong><code>6</code></strong>.</p><p>Some
features of the broker depend on information stored in the OpenWire commands from newer protocol
revisions and these may not work correctly if the store version is set to a lower value.&#160;
KahaDB stores from broker versions greater than 5.9.0 will in many cases still be readable
by the broker but will cause the broker to continue using the older store version meaning
newer features may not work as intended.&#160;</p><p>For KahaDB stores that
were created in versions prior to <strong>ActiveMQ 5.9.0</strong> it will be necessary
to manually set <strong><code>storeOpenWireVersion="6"</code></strong>
in order to start a broker without error.</p></td></tr></tbody></table></div><div
class="confluence-information-macro confluence-information-macro-information"><span
cla
 ss="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>For tuning locking properties see the
options listed at <a shape="rect" href="pluggable-storage-lockers.html">Pluggable storage
lockers.</a></p></div></div><p>&#160;</p><h3 id="KahaDB-SlowFileSystemAccessDiagnosticLogging">Slow
File System Access Diagnostic Logging</h3><p>You can configure a non zero threshold
in milliseconds for database updates. If database operation is slower than that threshold
(for example if you set it to <strong><code>500</code></strong>),
you may see messages like:</p><div class="panel" style="border-width: 1px;"><div
class="panelContent">
+</div></div><h3 id="KahaDB-KahaDBProperties">KahaDB Properties</h3><div
class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1"
rowspan="1" class="confluenceTh"><p>Property</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Default</p></th><th colspan="1"
rowspan="1" class="confluenceTh"><p>Comments</p></th></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>archiveCorruptedIndex</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
corrupted indexes found at startup will be archived (not deleted).</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>archiveDataLogs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
will move a message data log to the archi
 ve directory instead of deleting it.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>checkForCorruptJournalFiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
will check for corrupt journal files on startup and try and recover them.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>checkpointInterval</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>5000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Time (ms) before check-pointing the
journal.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>checksumJournalFiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Create a checksum for a journal file.
The presence of a checksum is requi
 red in order for the persistence adapter to be able to detect corrupt journal files.</p><p>Before
<strong>ActiveMQ 5.9.0</strong>: the default is <strong><code>false</code></strong>.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>cleanupInterval</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>30000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The interval (in ms) between consecutive
checks that determine which journal files, if any, are eligible for removal from the message
store. An eligible journal file is one that has no outstanding references.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>compactAcksAfterNoGC</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
when the acknowledgement compaction feature is enabled this value controls how many store

 GC cycles must be completed with no other files being cleaned up before the compaction logic
is triggered to possibly compact older acknowledgements spread across journal files into a
new log file.&#160; The lower the value set the faster the compaction may occur which
can impact performance if it runs to often.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>compactAcksIgnoresStoreGrowth</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:&#160;when
the acknowledgement compaction feature is enabled this value controls whether compaction is
run when the store is still growing or if it should only occur when the store has stopped
growing (either due to idle or store limits reached).&#160; If enabled the compaction
runs regardless of the store still having room or being active which can decrease overall
performance but reclaim s
 pace faster.&#160;</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>concurrentStoreAndDispatchQueues</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Enable the dispatching of Queue messages
to interested clients to happen concurrently with message storage.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>concurrentStoreAndDispatchTopics</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Enable the dispatching of Topic messages
to interested clients to happen concurrently with message storage</p><div class="confluence-information-macro
confluence-information-macro-warning"><span class="aui-icon aui-icon-small aui-iconfont-error
confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>Enabling
this property is 
 not recommended.</p></div></div></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>directory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>activemq-data</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The path to the directory to use
to store the message store data and log files.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>directoryArchive</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>null</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Define the directory to move data
logs to when they all the messages they contain have been consumed.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>enableAckCompaction</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting controls whether t
 he store will perform periodic compaction of older journal log files that contain only Message
acknowledgements. By compacting these older acknowledgements into new journal log files the
older files can be removed freeing space and allowing the message store to continue to operate
without hitting store size limits.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>enableIndexWriteAsync</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
the index is updated asynchronously.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>enableJournalDiskSyncs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>true</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><span>Ensure every journal
write is followed by a disk sync (JMS durability requirement).</span></p><div
class="conflu
 ence-information-macro confluence-information-macro-warning"><span class="aui-icon
aui-icon-small aui-iconfont-error confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>This property is deprecated as of <strong>ActiveMQ</strong>
<strong>5.14.0</strong>.</p><p>From <strong>ActiveMQ</strong>
<strong>5.14.0</strong>: see <span style="color: rgb(34,34,34);"><strong><code>journalDiskSyncStrategy</code></strong>.</span></p></div></div></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>ignoreMissingJournalfiles</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>If <strong><code>true</code></strong>,
reports of missing journal files are ignored.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>indexCacheSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10000</code></p></td><td
colspan
 ="1" rowspan="1" class="confluenceTd"><p>Number of index pages cached in memory.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>indexDirectory</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd">&#160;</td><td colspan="1" rowspan="1"
class="confluenceTd"><p><span>From <strong>ActiveMQ 5.10.0</strong>:
If set, configures where the KahaDB index files (<strong><code>db.data</code></strong>
and&#160;<strong><code>db.redo</code></strong>) will be stored.
If not set, the index files are stored in the directory specified by the&#160;<strong><code>directory</code></strong>
attribute.</span></p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>indexWriteBatchSize</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>1000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Number of indexes written in a batch.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code><span>journalD
 iskSyncInterval</span></code></p></td><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>1000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Interval (ms) for when to perform
a disk sync when&#160;<strong><code>journalDiskSyncStrategy=periodic</code></strong>.
A sync will only be performed if a write has occurred to the journal since the last disk sync
or when the journal rolls over to a new journal file.</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code><span>journalDiskSyncStrategy</span></code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>always</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting configures the disk sync policy. The list of available sync strategies are (in
order of decreasing safety, and increasing performance):</p><ul><li><p><strong><code>always</code></strong>
<span>Ensure every journal write is followed by a disk sync (JM
 S durability requirement). This is the safest option but is also the slowest because it requires
a sync after every message write. This is equivalent to the deprecated property&#160;<strong><code>enableJournalDiskSyncs=true</code></strong>.</span></p></li><li><p><strong><code>periodic</code></strong>
<span style="color: rgb(34,34,34);">The disk will be synced at set intervals (if a write
has occurred) instead of after every journal write which will reduce the load on the disk
and should improve throughput</span>. The disk will also be synced when rolling over
to a new journal file. The default interval is 1 second. The default interval offers very
good performance, whilst being safer than&#160;<strong><code>never</code></strong>
disk syncing, as data loss is limited to a maximum of 1 second's worth. See <strong><code>journalDiskSyncInterval</code></strong>
to change the frequency of disk syncs.</p></li><li><p><strong><code>never</code></strong>
A sync will never be explicitly called
  and it will be up to the operating system to flush to disk. This is equivalent to setting
the deprecated property <strong><code>enableJournalDiskSyncs=false</code></strong>.
This is the fastest option but is the least safe as there's no guarantee as to when data is
flushed to disk. Consequently message loss <em>can</em> occur on broker failure.</p></li></ul></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>journalMaxFileLength</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>32mb</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>A hint to set the maximum size of
the message data logs.</p></td></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>maxAsyncJobs</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>10000</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>The maximum number of asynchronous
messages that will be queued awaiting storage (should be the same as the
  number of concurrent MessageProducers).</p></td></tr><tr><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>preallocationScope</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>entire_journal</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.14.0</strong>:
this setting configures how journal data files are preallocated. The default strategy preallocates
the journal file on first use using the appender thread.&#160;</p><ul><li><strong><code>entire_journal</code></strong>
will preallocate the journal file on first use using the appender thread<br clear="none"><p>&#160;</p></li><li><p><strong><code>entire_journal_async</code></strong>
will use preallocate ahead of time in a separate thread.</p></li><li><p><strong><code>none</code></strong>
disables preallocation.</p></li></ul><p>On SSD, using&#160;<strong><code>entire_journal_async</code></strong>
avoids delaying writes pending preallocation on first use.</p><p><st
 rong>Note</strong>: on HDD the additional thread contention for disk has a negative
impact. Therefore use the default.</p></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>preallocationStrategy</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p><code>sparse_file</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>From <strong>ActiveMQ 5.12.0</strong>:&#160;This
setting configures how the broker will try to preallocate the journal files when a new journal
file is needed.</p><ul><li><p><strong><code>sparse_file</code></strong>
- sets the file length, but does not populate it with any data.</p></li><li><p><strong><code>os_kernel_copy</code></strong>
- delegates the preallocation to the Operating System.</p></li><li><p><strong><code>zeros</code></strong>&#160;
- each preallocated journal file contains nothing but <strong><code>0x00</code></strong>
throughout.</p></li></ul></td></tr><tr><td colspan="1"
rowspan="1" class="confluenceTd">
 <p><code>storeOpenWireVersion</code></p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p><code>11</code></p></td><td
colspan="1" rowspan="1" class="confluenceTd"><p>Determines the version of OpenWire
commands that are marshaled to the KahaDB journal.&#160;</p><p>Before <strong>ActiveMQ
5.12.0</strong>: the default value is <strong><code>6</code></strong>.</p><p>Some
features of the broker depend on information stored in the OpenWire commands from newer protocol
revisions and these may not work correctly if the store version is set to a lower value.&#160;
KahaDB stores from broker versions greater than 5.9.0 will in many cases still be readable
by the broker but will cause the broker to continue using the older store version meaning
newer features may not work as intended.&#160;</p><p>For KahaDB stores that
were created in versions prior to <strong>ActiveMQ 5.9.0</strong> it will be necessary
to manually set <strong><code>storeOpenWireVersion="6"</code></strong>
in order to s
 tart a broker without error.</p></td></tr></tbody></table></div><div
class="confluence-information-macro confluence-information-macro-information"><span
class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>For tuning locking properties see the
options listed at <a shape="rect" href="pluggable-storage-lockers.html">Pluggable storage
lockers.</a></p></div></div><p>&#160;</p><h3 id="KahaDB-SlowFileSystemAccessDiagnosticLogging">Slow
File System Access Diagnostic Logging</h3><p>You can configure a non zero threshold
in milliseconds for database updates. If database operation is slower than that threshold
(for example if you set it to <strong><code>500</code></strong>),
you may see messages like:</p><div class="panel" style="border-width: 1px;"><div
class="panelContent">
 <p><code>Slow KahaDB access: cleanup took 1277 | org.apache.activemq.store.kahadb.MessageDatabase
| ActiveMQ Journal Checkpoint Worker</code></p>
 </div></div><p>You can configure a threshold used to log these messages
by using a system property and adjust it to your disk speed so that you can easily pick up
runtime anomalies.</p><div class="panel" style="border-width: 1px;"><div class="panelContent">
 <p><code>-Dorg.apache.activemq.store.kahadb.LOG_SLOW_ACCESS_TIME=1500</code></p>



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