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.  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>: 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).  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. </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"> </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 <strong><code>db.redo</code></strong>) will be stored. If not set, the
index files are stored in the directory specified by
the <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 <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 <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 <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. </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 <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>: 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>  - 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. </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.  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. </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> </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.  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>: 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).  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. </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"> </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 <strong><code>db.redo</code></strong>) will be stored. If not set, the
index files are stored in the directory specified by
the <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 <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 <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 <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. </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> </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 <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>: 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>  - 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. </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.  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. </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> </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>
