75 lines
2.8 KiB
Plaintext
75 lines
2.8 KiB
Plaintext
[[heap-size]]
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=== Set JVM heap size via jvm.options
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By default, Elasticsearch tells the JVM to use a heap with a minimum
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and maximum size of 1 GB. When moving to production, it is
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important to configure heap size to ensure that Elasticsearch has enough
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heap available.
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Elasticsearch will assign the entire heap specified in <<jvm-options,jvm.options>>
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via the Xms (minimum heap size) and Xmx (maximum heap size) settings.
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The value for these setting depends on the amount of RAM available on
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your server. Good rules of thumb are:
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* Set the minimum heap size (Xms) and maximum heap size (Xmx) to be
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equal to each other.
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* The more heap available to Elasticsearch, the more memory it can use for
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caching. But note that too much heap can subject you to long garbage
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collection pauses.
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* Set Xmx to no more than 50% of your physical RAM, to ensure that there
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is enough physical RAM left for kernel file system caches.
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* Don’t set Xmx to above the cutoff that the JVM uses for compressed
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object pointers (compressed oops); the exact cutoff varies but is
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near 32 GB. You can verify that you are under the limit by looking
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for a line in the logs like the following:
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+
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heap size [1.9gb], compressed ordinary object pointers [true]
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* Even better, try to stay below the threshold for zero-based
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compressed oops; the exact cutoff varies but 26 GB is safe on most
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systems, but can be as large as 30 GB on some systems. You can verify
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that you are under the limit by starting Elasticsearch with the JVM
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options `-XX:+UnlockDiagnosticVMOptions -XX:+PrintCompressedOopsMode`
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and looking for a line like the following:
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+
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--
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heap address: 0x000000011be00000, size: 27648 MB, zero based Compressed Oops
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showing that zero-based compressed oops are enabled instead of
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heap address: 0x0000000118400000, size: 28672 MB, Compressed Oops with base: 0x00000001183ff000
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--
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Here are examples of how to set the heap size via the jvm.options file:
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[source,txt]
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------------------
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-Xms2g <1>
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-Xmx2g <2>
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------------------
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<1> Set the minimum heap size to 2g.
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<2> Set the maximum heap size to 2g.
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It is also possible to set the heap size via an environment variable.
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This can be done by commenting out the `Xms` and `Xmx` settings
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in the jvm.options file and setting these values via `ES_JAVA_OPTS`:
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[source,sh]
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------------------
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ES_JAVA_OPTS="-Xms2g -Xmx2g" ./bin/elasticsearch <1>
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ES_JAVA_OPTS="-Xms4000m -Xmx4000m" ./bin/elasticsearch <2>
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------------------
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<1> Set the minimum and maximum heap size to 2 GB.
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<2> Set the minimum and maximum heap size to 4000 MB.
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NOTE: Configuring the heap for the <<windows-service,Windows service>>
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is different than the above. The values initially populated for the
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Windows service can be configured as above but are different after the
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service has been installed. Consult the
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<<windows-service,Windows service documentation>> for additional
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details.
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