mirror of
https://github.com/matrix-org/dendrite
synced 2024-11-05 23:48:58 +01:00
89 lines
3.8 KiB
Markdown
89 lines
3.8 KiB
Markdown
# Profiling Dendrite
|
|
|
|
If you are running into problems with Dendrite using excessive resources (e.g. CPU or RAM) then you can use the profiler to work out what is happening.
|
|
|
|
Dendrite contains an embedded profiler called `pprof`, which is a part of the standard Go toolchain.
|
|
|
|
## Enable the profiler
|
|
|
|
To enable the profiler, start Dendrite with the `PPROFLISTEN` environment variable. This variable specifies which address and port to listen on, e.g.
|
|
|
|
```
|
|
PPROFLISTEN=localhost:65432 ./bin/dendrite-monolith-server ...
|
|
```
|
|
|
|
If pprof has been enabled successfully, a log line at startup will show that pprof is listening:
|
|
|
|
```
|
|
WARN[2020-12-03T13:32:33.669405000Z] [/Users/neilalexander/Desktop/dendrite/internal/log.go:87] SetupPprof
|
|
Starting pprof on localhost:65432
|
|
```
|
|
|
|
All examples from this point forward assume `PPROFLISTEN=localhost:65432` but you may need to adjust as necessary for your setup.
|
|
|
|
## Profiling CPU usage
|
|
|
|
To examine where CPU time is going, you can call the `profile` endpoint:
|
|
|
|
```
|
|
http://localhost:65432/debug/pprof/profile?seconds=30
|
|
```
|
|
|
|
The profile will run for the specified number of `seconds` and then will produce a result.
|
|
|
|
### Examine a profile using the Go toolchain
|
|
|
|
If you have Go installed and want to explore the profile, you can invoke `go tool pprof` to start the profile directly. The `-http=` parameter will instruct `go tool pprof` to start a web server providing a view of the captured profile:
|
|
|
|
```
|
|
go tool pprof -http=localhost:23456 http://localhost:65432/debug/pprof/profile?seconds=30
|
|
```
|
|
|
|
You can then visit `http://localhost:23456` in your web browser to see a visual representation of the profile. Particularly usefully, in the "View" menu, you can select "Flame Graph" to see a proportional interactive graph of CPU usage.
|
|
|
|
### Download a profile to send to someone else
|
|
|
|
If you don't have the Go tools installed but just want to capture the profile to send to someone else, you can instead use `curl` to download the profiler results:
|
|
|
|
```
|
|
curl -O http://localhost:65432/debug/pprof/profile?seconds=30
|
|
```
|
|
|
|
This will block for the specified number of seconds, capturing information about what Dendrite is doing, and then produces a `profile` file, which you can send onward.
|
|
|
|
## Profiling memory usage
|
|
|
|
To examine where memory usage is going, you can call the `heap` endpoint:
|
|
|
|
```
|
|
http://localhost:65432/debug/pprof/heap
|
|
```
|
|
|
|
The profile will return almost instantly.
|
|
|
|
### Examine a profile using the Go toolchain
|
|
|
|
If you have Go installed and want to explore the profile, you can invoke `go tool pprof` to start the profile directly. The `-http=` parameter will instruct `go tool pprof` to start a web server providing a view of the captured profile:
|
|
|
|
```
|
|
go tool pprof -http=localhost:23456 http://localhost:65432/debug/pprof/heap
|
|
```
|
|
|
|
You can then visit `http://localhost:23456` in your web browser to see a visual representation of the profile. The "Sample" menu lets you select between four different memory profiles:
|
|
|
|
* `inuse_space`: Shows how much actual heap memory is allocated per function (this is generally the most useful profile when diagnosing high memory usage)
|
|
* `inuse_objects`: Shows how many heap objects are allocated per function
|
|
* `alloc_space`: Shows how much memory has been allocated per function (although that memory may have since been deallocated)
|
|
* `alloc_objects`: Shows how many allocations have been made per function (although that memory may have since been deallocated)
|
|
|
|
Also in the "View" menu, you can select "Flame Graph" to see a proportional interactive graph of the memory usage.
|
|
|
|
### Download a profile to send to someone else
|
|
|
|
If you don't have the Go tools installed but just want to capture the profile to send to someone else, you can instead use `curl` to download the profiler results:
|
|
|
|
```
|
|
curl -O http://localhost:65432/debug/pprof/heap
|
|
```
|
|
|
|
This will almost instantly produce a `heap` file, which you can send onward.
|