{ “title”: “Use FE profiler to generate flame graph”, “language”: “en” }

introduce

In versions 2.1.4 and above of Doris, there will be a profile_fe.sh script in the fe deployment directory ${DORIS_FE_HOME}/bin. This script can use the async-profiler tool to generate a flame graph of fe, which can be used to identify the bottleneck points of fe.

:::note Note: The async profiler tool currently only supports Linux and MacOS systems, and does not currently support Windows systems :::

The usage cases are as follows

$ # By default, monitor FE for 10 seconds to generate a flame graph
$ ${DORIS_FE_HOME}/bin/profile_fe.sh

$ # Set listening fe for 30 seconds to generate a flame graph
$ PROFILE_SECONDS=30 ${DORIS_FE_HOME}/bin/profile_fe.sh

After running the above command, it will listen to fe for a period of time. During this period, we need to repeatedly send key queries to this FE so that the async-profiler can collect FE's key stack frame information. After collecting stack frame information, the script will generate an HTML flame graph file in the ${DORIS_FE_HOME}/log directory. Generally, the bottleneck of fe will appear as a flat top (short and wide) in the flame graph. We can optimize the performance of the code corresponding to these stack frames.

The following is an example of a flame graph

Using async-profiler in lower versions of fe

In versions below 2.1.4, two files need to be manually downloaded

  1. Download ap-loader-all-3.0-8.jar to the ${DORIS_FE_HOME}/libdirectory
  2. Download profile_fe.sh to the ${DORIS_FE_HOME}/bindirectory
  3. Just run profile_fe.sh