ProfileEndpoints

Provides HTTP endpoints (and an optional HTTP server) that wrap the profiling functionality exposed from existing Julia packages, to allow introspecting a live-running Julia process to interrogate its performance characteristics.

Endpoints

CPU Profile

• /profile endpoint to record a CPU profile for a given duration using Profile.@profile.
  • Default query params: /profile?n=1e8&delay=0.01&duration=10&pprof=true
• /profile_start to start the CPU profiler (without specifying a duration to run for).
  • Default query params: /profile_start?n=1e8&delay=0.01
• /profile_stop to stop the CPU profiler and return the profile.
  • Default query params: /profile_stop?pprof=true

Allocation Profile

• /allocs_profile endpoint to record an allocations profile for a given duration using Profile.Allocs.@profile.
  • Default query params: /allocs_profile?sample_rate=0.0001&duration=10
• /allocs_profile_start to start the allocation profiler (without specifying a duration to run for).
  • Default query params: /allocs_profile_start?sample_rate=0.0001
• /allocs_profile_stop to stop the allocation profiler and return the profile.
  • Takes no query params.

Heap Snapshot

• /heap_snapshot endpoint to take a heap snapshot with Profile.take_heap_snapshot.
  • Default query params: /heap_snapshot?all_one=false

Task Backtraces

• /task_backtraces endpoint to collect task backtraces. Only available in Julia v1.10+.
  • Default query params: none.

Examples

Start the server on your production process

julia> Threads.nthreads()
4

julia> t = @async ProfileEndpoints.serve_profiling_server()  # Start the profiling server in the background
[ Info: Starting HTTP profiling server on port 16825
Task (runnable) @0x0000000113c8d660

julia> for _ in 1:100 peakflops() end  # run stuff to profile (locks up the REPL)

CPU Profile

Collect a CPU profile:

$ curl '127.0.0.1:16825/profile?delay=0.01&duration=3' --output prof1.pb.gz

And view it in PProf:

julia> using PProf

julia> PProf.refresh(file="./prof1.pb.gz")

Allocation Profile

Collect an allocation profile (requires Julia v1.8+):

$ curl '127.0.0.1:16825/allocs_profile?sample_rate=0.0001&duration=3' --output allocs_prof1.pb.gz

And view it in PProf:

julia> using PProf

julia> PProf.refresh(file="./allocs_prof1.pb.gz")

Heap Snapshot

Take a heap snapshot (requires Julia v1.9+):

$ curl '127.0.0.1:16825/heap_snapshot?all_one=false' --output prof1.heapsnapshot

And upload it in the Chrome DevTools snapshot viewer to explore the heap. In Chrome View > Developer > Developer Tools, select the Memory tab, and press the Load button to upload the file.

Task Backtraces

Collect task backtraces (requires Julia v1.10+):

$ curl '127.0.0.1:16825/task_backtraces' --output task_backtraces.txt