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136 lines
4.2 KiB
ReStructuredText
136 lines
4.2 KiB
ReStructuredText
.. _debugging:
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.. todo::
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This page mostly duplicates syncthing(1). Needs merging.
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Debugging Syncthing
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===================
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There's a lot that happens behind the covers, and Syncthing is generally
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quite silent about it. A number of environment variables can be used to
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set the logging to verbose for various parts of the program, and to
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enable profiling.
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Environment Variables
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---------------------
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STTRACE
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~~~~~~~
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The environment variable ``STTRACE`` can be set to a comma separated
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list of "facilities", to enable extra debugging information for said
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facility. A facility generally maps to a Go package, although there are
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a few extra that map to parts of the ``main`` package. Currently, the
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following facilities are supported (an up to date list is always printed
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by ``syncthing --help``):
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- ``beacon`` (the beacon package)
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- ``discover`` (the discover package)
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- ``events`` (the events package)
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- ``files`` (the files package)
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- ``http`` (the main package; HTTP requests)
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- ``net`` (the main package; connections & network messages)
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- ``model`` (the model package)
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- ``scanner`` (the scanner package)
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- ``stats`` (the stats package)
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- ``upnp`` (the upnp package)
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- ``xdr`` (the xdr package)
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- ``all`` (all of the above)
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The debug output is often of the kind that it doesn't make much sense
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without looking at the code. The purpose of the different packages /
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facilities are something like this:
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- ``beacon`` sends and receives UDP broadcasts used by the local
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discovery system. Debugging here will show which interfaces and
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addresses are selected for broadcasts, etc.
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- ``discover`` sends and receives local discovery packets. Debugging
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here will output the parsed packets, nodes that get registered etc.
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- ``files`` keeps track of lists of files with metadata and figures out
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which is the newest version of each.
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- ``net`` shows connection attempts, incoming connections, and the low
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level error when connection attempts fail.
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- ``model`` is the largest chunk of the system; this is where pulling
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of out of date files happens, indexes are sent and received, and incoming
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requests for file chunks are logged.
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- ``scanner`` is the local filesystem scanner. Debugging here will
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output information about changed and unchanged files.
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- ``upnp`` is the upnp talker.
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- ``xdr`` is the low level protocol encoder. Debugging here will output
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all bytes sent/received over the sync connection. Very verbose.
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- ``all`` simply enables debugging of all facilities.
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Enabling any of the facilities will also change the log format to
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include microsecond timestamps and file names plus line numbers. This
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can be used to enable this extra information on the normal logging
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level, without enabling any debugging: ``STTRACE=somethingnonexistent``
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for example.
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Under Unix (including Mac) the easiest way to run Syncthing with an
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environment variable set is to prepend the variable to the command line.
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I.e:
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``$ STTRACE=model syncthing``
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On windows, it needs to be set prior to running Syncthing.
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::
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C:\> set STTRACE=model
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C:\> syncthing
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STPROFILER
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~~~~~~~~~~
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The ``STPROFILER`` environment variable sets the listen address for the
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HTTP profiler. If set to for example ``:9090`` the profiler will start
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and listen on port 9090. http://localhost:9090/debug/pprof is then the
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address to the profiler. Se ``go tool pprof`` for more information.
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STGUIASSETS
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~~~~~~~~~~~
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Directory to load GUI assets from. Overrides compiled in assets. Useful
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for developing webgui, commonly use ``STGUIASSETS=gui bin/syncthing``
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STCPUPROFILE
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~~~~~~~~~~~~
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Write a CPU profile to ``cpu-$pid.pprof`` on exit.
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STHEAPPROFILE
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~~~~~~~~~~~~~
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Write heap profiles to ``heap-$pid-$timestamp.pprof`` each time
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heap usage increases.
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STBLOCKPROFILE
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~~~~~~~~~~~~~~
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Write block profiles to ``block-$pid-$timestamp.pprof`` every 20
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seconds.
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STPERFSTATS
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~~~~~~~~~~~
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Write running performance statistics to ``perf-$pid.csv``. Not supported on
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Windows.
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STNOUPGRADE
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~~~~~~~~~~~
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Disable automatic upgrades.
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GOMAXPROCS
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~~~~~~~~~~
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Set the maximum number of CPU cores to use. Defaults to all available
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CPU cores.
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GOGC
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~~~~
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Percentage of heap growth at which to trigger GC. Default is 100. Lower
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numbers keep peak memory usage down, at the price of CPU usage (ie.
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performance)
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