Compaction file swap issue on CouchDB 3.x + Windows

[pavellzubkov]

Description

Today I can't get view result with next error
log:

{{badmatch,{error,ebusy}},
 [{couch_mrview_compactor,swap_compacted,2,
                          [{file,"src/couch_mrview_compactor.erl"},
                           {line,232}]},
  {couch_index,commit_compacted,2,[{file,"src/couch_index.erl"},{line,406}]},
  {couch_index,handle_call,3,[{file,"src/couch_index.erl"},{line,199}]},
  {gen_server,try_handle_call,4,[{file,"gen_server.erl"},{line,636}]},
  {gen_server,handle_msg,6,[{file,"gen_server.erl"},{line,665}]},
  {proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,247}]}]}

server resp with status 500. err same as above . message -
{gen_server,call,[<0.13136.57>,{get_state,16303},infinity]}

Steps to Reproduce

unknown

Expected Behaviour

normal resp

Your Environment

• CouchDB version used: 3.0
• Browser name and version: Chrome
• Operating system and version: image: couchdb:3.0.0 on Docker

Additional Context

after manual restart docker container problem gone

[wohali]

@pavellzubkov How long did the problem persist?

ebusy means the file was busy and in use. The error message suggests the compactor was finishing up compacting your view by swapping files around. It should have been a transient error.

/cc @nickva

[wohali]

Also, was this Docker container being hosted on Windows?

[pavellzubkov]

@wohali i've observe this problem about half hour. in active tasks tab in fauxton i've seen freezing compacton task on one of shards.
records from log file
lodjunk.txt

[wohali]

The error is coming from https://github.com/apache/couchdb/blob/master/src/couch_mrview/src/couch_mrview_compactor.erl#L232 which is where the compactor attempts to delete the index file after swapping.

One possible explanation is that you're running Docker on Windows, are mapping your data directory to a Windows file system, and something is still holding the file open. (File locking mechanisms on Windows differ from those on Unix.)

If this is Docker running on a Linux host, I'm not sure.

[pavellzubkov]

Yes. Docker on windows host. thanks for answer.

[wohali]

Reopening because this may be a problem for Windows CouchDB servers. Thanks for the report.

[wohali]

Sorry, my mistake. Looking at this code, it's not changed in years - we probably have never been able to support Windows-hosted Docker containers where the data directory is mapped to a local file system under Windows.

This probably should be added to the Docker documentation.