[GitHub] nickva edited a comment on issue #1596: Fix couch server race condition

[GitBox]

nickva edited a comment on issue #1596: Fix couch server race condition
URL: https://github.com/apache/couchdb/pull/1596#issuecomment-419169919
 
 
   The issue is reproducible with this script (in a remsh):
   
   ```
   f(FuzzIt), FuzzIt = fun(DbName, Tries, WaitMax) ->
           Ref = erlang:monitor(process, whereis(couch_server)),
           [begin
                [begin
                   CallRefs = [Open1Ref, DeleteRef, Open2Ref] = [make_ref(), 
make_ref(), make_ref()],
                   whereis(couch_server) ! {'$gen_call', {self(), Open1Ref}, 
{create, DbName, []}},
                   timer:sleep(W),
                   whereis(couch_server) ! {'$gen_call', {self(), DeleteRef}, 
{delete, DbName, []}},
                   whereis(couch_server) ! {'$gen_call', {self(), Open2Ref}, 
{open, DbName, []}},
                   [receive {R, _} -> ok end || R <- CallRefs]
                end || W <- lists:seq(0, WaitMax)]
            end || _ <- lists:seq(1, Tries)],
           receive  {'DOWN', Ref, _, _, Reason} ->  {bam, Reason}
           after 5000 -> nope
           end
   end.
   ```
   When run like this for example:
   ```
   FuzzIt(<<"blah">>, 100, 15).
   ```  
   
   It might help to have a few dbs open and some activity, like say a bunch of 
replication jobs running as well.
   
   The node would crash and possibly restart leaving something like this in the 
log:
   ```
   [error] 2018-09-06T17:01:48.085468Z node1@127.0.0.1 <0.243.0> -------- 
couch_server terminating with 
{function_clause,[{couch_server,'-handle_call/3-lc$^1/1-1-',[undefined],[{file,"src/couch_server.erl"},{line,434}]},{couch_server,handle_call,3,[{file,"src/couch_server.erl"},
   ```
   

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