Permalink
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
71 lines (52 sloc) 2.61 KB

Profiling

Note

Hi! If you're here because some developer told you to "grab a profile" and pointed to this page - welcome, and don't worry! The procedure is quick and painless.

Profiling is the process of figuring out what a program is doing -- where it's spending its time on the CPU and why it's allocated memory. The profiles are of two types - the "CPU profile" which shows which functions are using most CPU time and the "heap profile" that shows which functions have caused most memory to be allocated.

Neither of the profiles contain any private data about your setup - only what parts of the program are using resources.

Enable Debugging

Debugging must be enabled to be able to capture profiles. To enable debugging, open the advanced settings:

advanced-settings.png

Enable the "debugging" setting under "GUI", and then scroll down and Save. No restart is necessary.

gui-debugging.png

Capture a CPU profile

To get a CPU profile you need to visit a URL ending in /rest/debug/cpuprof. Assuming you are on the same computer as Syncthing and using the default settings, you should be able to do that by just clicking http://localhost:8384/rest/debug/cpuprof -- otherwise please adjust the host name and port as necessary.

The profiling starts when the page is requested and takes 30 seconds. During this time it will seem like nothing is happening and the browser is just waiting, hung, or "spinning". Don't worry - leave it be and have patience. Once done the profiling will result in a download called something like syncthing-cpu-windows-amd64-v0.14.4-112233.pprof. This is the file to keep and send in, without modifying the file name as it tells us information necessary to interpret it.

Repeat the process twice and keep both files.

Capture a heap profile

To get a heap profile you need to visit a URL ending in /rest/debug/heapprof. The procedure is otherwise identical to the process for the CPU profile above, except the heap profile is downloaded instantaneously.

Assuming you are on the same computer as Syncthing and using the default settings, you should be able to do that by just clicking http://localhost:8384/rest/debug/heapprof -- otherwise please adjust the host name and port as necessary.

The profiling will result in a download called something like syncthing-heap-windows-amd64-v0.14.4-112233.pprof. This is the file to keep and send in, without modifying the file name as it tells us information necessary to interpret it.

Repeat the process twice and keep both files.