Steady-timer and rocksdb:low4 threads have high CPU usage, want to know what they are doing

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This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: steady-timer 和 rocksdb:low4 线程使用CPU很高,想知道它是做什么的。

| username: TiDBer_明明

【TiDB Usage Environment】Testing
【TiDB Version】4.0.9
【Reproduction Path】What operations were performed when the issue occurred
【Encountered Issue: Issue Phenomenon and Impact】
【Resource Configuration】
【Attachments: Screenshots/Logs/Monitoring】

| username: TiDBer_UUTlqVvZ | Original post link

Let me give it a try.

The high CPU usage of the steady-timer and rocksdb:low4 threads might be due to certain operations in TiDB or TiKV.

Firstly, the steady-timer is likely a timer used to periodically execute tasks such as cleaning up expired cache or refreshing metadata. The high CPU usage of this thread might be because these tasks require significant computational resources or because the execution time of these tasks is too long.

Secondly, the rocksdb:low4 thread is probably a thread of the RocksDB storage engine in TiKV, mainly responsible for background data compression and merging operations. The high CPU usage of this thread might be due to the fact that data compression and merging operations require significant computational resources or because the data volume is too large.

To better pinpoint the issue, you can check the monitoring information of TiDB or TiKV, such as the Grafana monitoring panel, to understand the specific usage of the steady-timer and rocksdb:low4 threads. You can also check the logs of TiDB or TiKV to see if there are any anomalies or error messages.

| username: system | Original post link

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