Nodes hot threads
The nodes hot threads endpoint provides information about busy JVM threads for selected cluster nodes. It provides a unique view of the of activity each node.
Example
GET /_nodes/hot_threads
Path and HTTP methods
GET /_nodes/hot_threads
GET /_nodes/<nodeId>/hot_threads
Path parameters
You can include the following optional path parameter in your request.
| Parameter | Type | Description |
|---|---|---|
| nodeId | String | A comma-separated list of node IDs used to filter results. Supports node filters. Defaults to _all. |
Query parameters
You can include the following query parameters in your request. All query parameters are optional.
| Parameter | Type | Description |
|---|---|---|
| snapshots | Integer | The number of samples of thread stacktraces. Defaults to 10. |
| interval | Time | The interval between consecutive samples. Defaults to 500ms. |
| threads | Integer | The number of the busiest threads to return information about. Defaults to 3. |
| ignore_idle_threads | Boolean | Don’t show threads that are in known idle states, such as waiting on a socket select or pulling from an empty task queue. Defaults to true. |
| type | String | Supported thread types are cpu, wait, or block. Defaults to cpu. |
| timeout | Time | Sets the time limit for node response. Default value is 30s. |
Example request
GET /_nodes/hot_threads
Example response
::: {opensearch}{F-ByTQzVQ3GQeYzQJArJGQ}{GxbcLdCATPWggOuQHJAoCw}{127.0.0.1}{127.0.0.1:9300}{dimr}{shard_indexing_pressure_enabled=true}
Hot threads at 2022-09-29T19:46:44.533Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true:
0.1% (455.5micros out of 500ms) cpu usage by thread 'ScheduledMetricCollectorsExecutor'
10/10 snapshots sharing following 2 elements
java.base@17.0.4/java.lang.Thread.sleep(Native Method)
org.opensearch.performanceanalyzer.collectors.ScheduledMetricCollectorsExecutor.run(ScheduledMetricCollectorsExecutor.java:100)
Response
Unlike the majority of OpenSearch API responses, this response is in a text format.
It consists of one section per each cluster node included in the response.
Each section starts with a single line containing the following segments:
| Line segment | Description |
|---|---|
::: | Line start (a distinct visual symbol). |
{global-eu-35} | Node name. |
{uFPbKLDOTlOmdnwUlKW8sw} | NodeId. |
{OAM8OT5CQAyasWuIDeVyUA} | EphemeralId. |
{global-eu-35.local} | Host name. |
{[gdv2:a284:2acv:5fa6:0:3a2:7260:74cf]:9300} | Host address. |
{dimr} | Node roles (d=data, i=ingest, m=cluster manager, r=remote cluster client). |
{zone=west-a2, shard_indexing_pressure_enabled=true} | Node attributes. |
Then information about threads of the selected type is provided.
::: {global-eu-35}{uFPbKLDOTlOmdnwUlKW8sw}{OAM8OT5CQAyasWuIDeVyUA}{global-eu-35.local}{[gdv2:a284:2acv:5fa6:0:3a2:7260:74cf]:9300}{dimr}{zone=west-a2, shard_indexing_pressure_enabled=true}
Hot threads at 2022-04-01T15:15:27.658Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true:
0.1% (645micros out of 500ms) cpu usage by thread 'opensearch[global-eu-35][transport_worker][T#7]'
4/10 snapshots sharing following 3 elements
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
java.base@11.0.14.1/java.lang.Thread.run(Thread.java:829)
::: {global-eu-62}{4knOxAdERlOB19zLQIT1bQ}{HJuZs2HiQ_-8Elj0Fvi_1g}{global-eu-62.local}{[gdv2:a284:2acv:5fa6:0:3a2:bba6:fe3f]:9300}{dimr}{zone=west-a2, shard_indexing_pressure_enabled=true}
Hot threads at 2022-04-01T15:15:27.659Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true:
18.7% (93.4ms out of 500ms) cpu usage by thread 'opensearch[global-eu-62][transport_worker][T#3]'
6/10 snapshots sharing following 3 elements
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
java.base@11.0.14.1/java.lang.Thread.run(Thread.java:829)
::: {global-eu-44}{8WW3hrkcTwGvgah_L8D_jw}{Sok7spHISFyol0jFV6i0kw}{global-eu-44.local}{[gdv2:a284:2acv:5fa6:0:3a2:9120:e79e]:9300}{dimr}{zone=west-a2, shard_indexing_pressure_enabled=true}
Hot threads at 2022-04-01T15:15:27.659Z, interval=500ms, busiestThreads=3, ignoreIdleThreads=true:
42.6% (212.7ms out of 500ms) cpu usage by thread 'opensearch[global-eu-44][write][T#5]'
2/10 snapshots sharing following 43 elements
java.base@11.0.14.1/sun.nio.ch.IOUtil.write1(Native Method)
java.base@11.0.14.1/sun.nio.ch.EPollSelectorImpl.wakeup(EPollSelectorImpl.java:254)
io.netty.channel.nio.NioEventLoop.wakeup(NioEventLoop.java:787)
io.netty.util.concurrent.SingleThreadEventExecutor.execute(SingleThreadEventExecutor.java:846)
io.netty.util.concurrent.SingleThreadEventExecutor.execute(SingleThreadEventExecutor.java:815)
io.netty.channel.AbstractChannelHandlerContext.safeExecute(AbstractChannelHandlerContext.java:989)
io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:796)
io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:758)
io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1020)
io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:311)
org.opensearch.transport.netty4.Netty4TcpChannel.sendMessage(Netty4TcpChannel.java:159)
app//org.opensearch.transport.OutboundHan...
Required permissions
If you use the Security plugin, make sure you set the following permissions: cluster:monitor/nodes/hot_threads.