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How to Profile Databend

CPU profiling​

go tool pprof -http="0.0.0.0:8081" http://localhost:8080/debug/pprof/profile?seconds=30

Open <your-ip>:8081 and select Flame Graph from the VIEW menus in the site header:

Memory profiling​

databend-query and databend-meta can be built optionally with jemalloc, which provides various memory profiling features.

Currently, it does not work on Mac, with either intel or ARM.

Enable memory profiling​

  1. Build databend-query with memory-profiling feature enabled:

    cargo build --bin databend-query --release --features memory-profiling

  2. Fire up databend, using environment variable MALLOC_CONF to enable memory profiling:

    MALLOC_CONF=prof:true,lg_prof_interval:30 ./target/release/databend-query

Generate heap profile​

Generate a call graph in pdf illustrating memory allocation during this interval:

jeprof --pdf ./target/release/databend-query heap.prof > heap.pdf

Fast jeprof​

jeprof is very slow for large heap analysis, the bottleneck is addr2line, if you want to speed up from 30 minutes to 3s, please use :

git clone https://github.com/gimli-rs/addr2line
cd addr2line
cargo b --examples -r
cp ./target/release/examples/addr2line <your-addr2line-find-with-whereis-addr2line>