- Elasticsearch Guide: other versions:
- Getting Started
- Set up Elasticsearch
- Installing Elasticsearch
- Configuring Elasticsearch
- Important Elasticsearch configuration
- Secure Settings
- Bootstrap Checks
- Heap size check
- File descriptor check
- Memory lock check
- Maximum number of threads check
- Max file size check
- Maximum size virtual memory check
- Maximum map count check
- Client JVM check
- Use serial collector check
- System call filter check
- OnError and OnOutOfMemoryError checks
- Early-access check
- G1GC check
- Important System Configuration
- Upgrading Elasticsearch
- Stopping Elasticsearch
- Set up X-Pack
- Breaking changes
- Breaking changes in 5.6
- Breaking changes in 5.5
- Breaking changes in 5.4
- Breaking changes in 5.3
- Breaking changes in 5.2
- Breaking changes in 5.1
- Breaking changes in 5.0
- Search and Query DSL changes
- Mapping changes
- Percolator changes
- Suggester changes
- Index APIs changes
- Document API changes
- Settings changes
- Allocation changes
- HTTP changes
- REST API changes
- CAT API changes
- Java API changes
- Packaging
- Plugin changes
- Filesystem related changes
- Path to data on disk
- Aggregation changes
- Script related changes
- API Conventions
- Document APIs
- Search APIs
- Aggregations
- Metrics Aggregations
- Avg Aggregation
- Cardinality Aggregation
- Extended Stats Aggregation
- Geo Bounds Aggregation
- Geo Centroid Aggregation
- Max Aggregation
- Min Aggregation
- Percentiles Aggregation
- Percentile Ranks Aggregation
- Scripted Metric Aggregation
- Stats Aggregation
- Sum Aggregation
- Top hits Aggregation
- Value Count Aggregation
- Bucket Aggregations
- Adjacency Matrix Aggregation
- Children Aggregation
- Date Histogram Aggregation
- Date Range Aggregation
- Diversified Sampler Aggregation
- Filter Aggregation
- Filters Aggregation
- Geo Distance Aggregation
- GeoHash grid Aggregation
- Global Aggregation
- Histogram Aggregation
- IP Range Aggregation
- Missing Aggregation
- Nested Aggregation
- Range Aggregation
- Reverse nested Aggregation
- Sampler Aggregation
- Significant Terms Aggregation
- Terms Aggregation
- Pipeline Aggregations
- Avg Bucket Aggregation
- Derivative Aggregation
- Max Bucket Aggregation
- Min Bucket Aggregation
- Sum Bucket Aggregation
- Stats Bucket Aggregation
- Extended Stats Bucket Aggregation
- Percentiles Bucket Aggregation
- Moving Average Aggregation
- Cumulative Sum Aggregation
- Bucket Script Aggregation
- Bucket Selector Aggregation
- Serial Differencing Aggregation
- Matrix Aggregations
- Caching heavy aggregations
- Returning only aggregation results
- Aggregation Metadata
- Returning the type of the aggregation
- Metrics Aggregations
- Indices APIs
- Create Index
- Delete Index
- Get Index
- Indices Exists
- Open / Close Index API
- Shrink Index
- Rollover Index
- Put Mapping
- Get Mapping
- Get Field Mapping
- Types Exists
- Index Aliases
- Update Indices Settings
- Get Settings
- Analyze
- Index Templates
- Shadow replica indices
- Indices Stats
- Indices Segments
- Indices Recovery
- Indices Shard Stores
- Clear Cache
- Flush
- Refresh
- Force Merge
- cat APIs
- Cluster APIs
- Query DSL
- Mapping
- Analysis
- Anatomy of an analyzer
- Testing analyzers
- Analyzers
- Normalizers
- Tokenizers
- Token Filters
- Standard Token Filter
- ASCII Folding Token Filter
- Flatten Graph Token Filter
- Length Token Filter
- Lowercase Token Filter
- Uppercase Token Filter
- NGram Token Filter
- Edge NGram Token Filter
- Porter Stem Token Filter
- Shingle Token Filter
- Stop Token Filter
- Word Delimiter Token Filter
- Word Delimiter Graph Token Filter
- Stemmer Token Filter
- Stemmer Override Token Filter
- Keyword Marker Token Filter
- Keyword Repeat Token Filter
- KStem Token Filter
- Snowball Token Filter
- Phonetic Token Filter
- Synonym Token Filter
- Synonym Graph Token Filter
- Compound Word Token Filters
- Reverse Token Filter
- Elision Token Filter
- Truncate Token Filter
- Unique Token Filter
- Pattern Capture Token Filter
- Pattern Replace Token Filter
- Trim Token Filter
- Limit Token Count Token Filter
- Hunspell Token Filter
- Common Grams Token Filter
- Normalization Token Filter
- CJK Width Token Filter
- CJK Bigram Token Filter
- Delimited Payload Token Filter
- Keep Words Token Filter
- Keep Types Token Filter
- Classic Token Filter
- Apostrophe Token Filter
- Decimal Digit Token Filter
- Fingerprint Token Filter
- Minhash Token Filter
- Character Filters
- Modules
- Index Modules
- Ingest Node
- Pipeline Definition
- Ingest APIs
- Accessing Data in Pipelines
- Handling Failures in Pipelines
- Processors
- Append Processor
- Convert Processor
- Date Processor
- Date Index Name Processor
- Fail Processor
- Foreach Processor
- Grok Processor
- Gsub Processor
- Join Processor
- JSON Processor
- KV Processor
- Lowercase Processor
- Remove Processor
- Rename Processor
- Script Processor
- Set Processor
- Split Processor
- Sort Processor
- Trim Processor
- Uppercase Processor
- Dot Expander Processor
- X-Pack APIs
- Info API
- Explore API
- Machine Learning APIs
- Close Jobs
- Create Datafeeds
- Create Jobs
- Delete Datafeeds
- Delete Jobs
- Delete Model Snapshots
- Flush Jobs
- Get Buckets
- Get Categories
- Get Datafeeds
- Get Datafeed Statistics
- Get Influencers
- Get Jobs
- Get Job Statistics
- Get Model Snapshots
- Get Records
- Open Jobs
- Post Data to Jobs
- Preview Datafeeds
- Revert Model Snapshots
- Start Datafeeds
- Stop Datafeeds
- Update Datafeeds
- Update Jobs
- Update Model Snapshots
- Security APIs
- Watcher APIs
- Migration APIs
- Deprecation Info APIs
- Definitions
- X-Pack Commands
- How To
- Testing
- Glossary of terms
- Release Notes
- 5.6.16 Release Notes
- 5.6.15 Release Notes
- 5.6.14 Release Notes
- 5.6.13 Release Notes
- 5.6.12 Release Notes
- 5.6.11 Release Notes
- 5.6.10 Release Notes
- 5.6.9 Release Notes
- 5.6.8 Release Notes
- 5.6.7 Release Notes
- 5.6.6 Release Notes
- 5.6.5 Release Notes
- 5.6.4 Release Notes
- 5.6.3 Release Notes
- 5.6.2 Release Notes
- 5.6.1 Release Notes
- 5.6.0 Release Notes
- 5.5.3 Release Notes
- 5.5.2 Release Notes
- 5.5.1 Release Notes
- 5.5.0 Release Notes
- 5.4.3 Release Notes
- 5.4.2 Release Notes
- 5.4.1 Release Notes
- 5.4.0 Release Notes
- 5.3.3 Release Notes
- 5.3.2 Release Notes
- 5.3.1 Release Notes
- 5.3.0 Release Notes
- 5.2.2 Release Notes
- 5.2.1 Release Notes
- 5.2.0 Release Notes
- 5.1.2 Release Notes
- 5.1.1 Release Notes
- 5.1.0 Release Notes
- 5.0.2 Release Notes
- 5.0.1 Release Notes
- 5.0.0 Combined Release Notes
- 5.0.0 GA Release Notes
- 5.0.0-rc1 Release Notes
- 5.0.0-beta1 Release Notes
- 5.0.0-alpha5 Release Notes
- 5.0.0-alpha4 Release Notes
- 5.0.0-alpha3 Release Notes
- 5.0.0-alpha2 Release Notes
- 5.0.0-alpha1 Release Notes
- 5.0.0-alpha1 Release Notes (Changes previously released in 2.x)
WARNING: Version 5.6 of Elasticsearch has passed its EOL date.
This documentation is no longer being maintained and may be removed. If you are running this version, we strongly advise you to upgrade. For the latest information, see the current release documentation.
Disable swapping
editDisable swapping
editMost operating systems try to use as much memory as possible for file system caches and eagerly swap out unused application memory. This can result in parts of the JVM heap or even its executable pages being swapped out to disk.
Swapping is very bad for performance, for node stability, and should be avoided at all costs. It can cause garbage collections to last for minutes instead of milliseconds and can cause nodes to respond slowly or even to disconnect from the cluster. In a resilient distributed system, it’s more effective to let the operating system kill the node.
There are three approaches to disabling swapping. The preferred option is to completely disable swap. If this is not an option, whether or not to prefer minimizing swappiness versus memory locking is dependent on your environment.
Disable all swap files
editUsually Elasticsearch is the only service running on a box, and its memory usage is controlled by the JVM options. There should be no need to have swap enabled.
On Linux systems, you can disable swap temporarily by running:
sudo swapoff -a
To disable it permanently, you will need to edit the /etc/fstab
file and
comment out any lines that contain the word swap
.
On Windows, the equivalent can be achieved by disabling the paging file entirely
via System Properties → Advanced → Performance → Advanced → Virtual memory
.
Configure swappiness
editAnother option available on Linux systems is to ensure that the sysctl value
vm.swappiness
is set to 1
. This reduces the kernel’s tendency to swap and
should not lead to swapping under normal circumstances, while still allowing the
whole system to swap in emergency conditions.
Enable bootstrap.memory_lock
editAnother option is to use
mlockall on
Linux/Unix systems, or
VirtualLock
on Windows, to try to lock the process address space into RAM, preventing any
Elasticsearch memory from being swapped out. This can be done, by adding this
line to the config/elasticsearch.yml
file:
bootstrap.memory_lock: true
mlockall
might cause the JVM or shell session to exit if it tries to
allocate more memory than is available!
After starting Elasticsearch, you can see whether this setting was applied
successfully by checking the value of mlockall
in the output from this
request:
GET _nodes?filter_path=**.mlockall
If you see that mlockall
is false
, then it means that the mlockall
request has failed. You will also see a line with more information in the logs
with the words Unable to lock JVM Memory
.
The most probable reason, on Linux/Unix systems, is that the user running Elasticsearch doesn’t have permission to lock memory. This can be granted as follows:
-
.zip
and.tar.gz
-
Set
ulimit -l unlimited
as root before starting Elasticsearch, or setmemlock
tounlimited
in/etc/security/limits.conf
. - RPM and Debian
-
Set
MAX_LOCKED_MEMORY
tounlimited
in the system configuration file (or see below for systems usingsystemd
). -
Systems using
systemd
-
Set
LimitMEMLOCK
toinfinity
in the systemd configuration.
Another possible reason why mlockall
can fail is that the temporary directory
(usually /tmp
) is mounted with the noexec
option. This can be solved by
specifying a new temp directory using the ES_JAVA_OPTS
environment variable:
export ES_JAVA_OPTS="$ES_JAVA_OPTS -Djava.io.tmpdir=/path/to/temp/dir" ./bin/elasticsearch
or setting this JVM flag in the jvm.options configuration file.