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OpenSearch/docs/reference/setup/important-settings/heap-size.asciidoc

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Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
[[heap-size]]
=== Setting the heap size
By default, Elasticsearch tells the JVM to use a heap with a minimum and maximum
size of 1 GB. When moving to production, it is important to configure heap size
to ensure that Elasticsearch has enough heap available.
Elasticsearch will assign the entire heap specified in
<<jvm-options,jvm.options>> via the `Xms` (minimum heap size) and `Xmx` (maximum
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
heap size) settings. You should set these two settings to be equal to each
other.
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
Minor cluster coordination docs fixes (#42111) Fixes a typo and a badly-formatted warning.
2019-05-15 09:26:04 -04:00
The value for these settings depends on the amount of RAM available on your
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
server:
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
* Set `Xmx` and `Xms` to no more than 50% of your physical RAM. {es} requires
memory for purposes other than the JVM heap and it is important to leave
space for this. For instance, {es} uses off-heap buffers for efficient
network communication, relies on the operating system's filesystem cache for
efficient access to files, and the JVM itself requires some memory too. It is
normal to observe the {es} process using more memory than the limit
configured with the `Xmx` setting.
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
* Set `Xmx` and `Xms` to no more than the threshold that the JVM uses for
compressed object pointers (compressed oops); the exact threshold varies but
is near 32 GB. You can verify that you are under the threshold by looking for a
line in the logs like the following:
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
+
heap size [1.9gb], compressed ordinary object pointers [true]
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
* Ideally set `Xmx` and `Xms` to no more than the threshold for zero-based
compressed oops; the exact threshold varies but 26 GB is safe on most
systems, but can be as large as 30 GB on some systems. You can verify that
you are under this threshold by starting {es} with the JVM options
`-XX:+UnlockDiagnosticVMOptions -XX:+PrintCompressedOopsMode` and looking for
a line like the following:
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
+
--
heap address: 0x000000011be00000, size: 27648 MB, zero based Compressed Oops
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
showing that zero-based compressed oops are enabled. If zero-based compressed
oops are not enabled then you will see a line like the following instead:
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
heap address: 0x0000000118400000, size: 28672 MB, Compressed Oops with base: 0x00000001183ff000
--
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
The more heap available to {es}, the more memory it can use for its internal
caches, but the less memory it leaves available for the operating system to use
for the filesystem cache. Also, larger heaps can cause longer garbage
collection pauses.
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
Here are examples of how to set the heap size via the jvm.options file:
[source,txt]
------------------
-Xms2g <1>
-Xmx2g <2>
------------------
<1> Set the minimum heap size to 2g.
<2> Set the maximum heap size to 2g.
It is also possible to set the heap size via an environment variable. This can
be done by commenting out the `Xms` and `Xmx` settings in the
<<jvm-options,`jvm.options`>> file and setting these values via `ES_JAVA_OPTS`:
[source,sh]
------------------
ES_JAVA_OPTS="-Xms2g -Xmx2g" ./bin/elasticsearch <1>
ES_JAVA_OPTS="-Xms4000m -Xmx4000m" ./bin/elasticsearch <2>
------------------
<1> Set the minimum and maximum heap size to 2 GB.
<2> Set the minimum and maximum heap size to 4000 MB.
NOTE: Configuring the heap for the <<windows-service,Windows service>> is
Recognise direct buffers in heap size docs (#42070) This commit slightly reworks the recommendations in the docs about setting the heap size: * the "rules of thumb" are actually instructions that should be followed * the reason for setting `Xmx` to 50% of the heap size is more subtle than just leaving space for the filesystem cache * it is normal to see Elasticsearch using more memory than `Xmx` * replace `cutoff` and `limit` with `threshold` since all three terms are used interchangeably * since we recommend setting `Xmx` equal to `Xms`, avoid talking about setting `Xmx` in isolation Relates #41954
2019-05-10 08:55:27 -04:00
different than the above. The values initially populated for the Windows
service can be configured as above but are different after the service has been
Reorganize configuring Elasticsearch docs This commit reorganizes some of the content in the configuring Elasticsearch section of the docs. The changes are: - move JVM options out of system configuration into configuring Elasticsearch - move JVM options to its own page of the docs - move configuring the heap to important Elasticsearch settings - move configuring the heap to its own page of the docs - move all important settings to individual pages in the docs - remove bootstrap.memory_lock from important settings, this is covered in the swap section of system configuration Relates #27755
2017-12-12 10:24:37 -05:00
installed. Consult the <<windows-service,Windows service documentation>> for
additional details.