Hi Gal, You are indeed right in thinking that this is not a show-stopper. It's essentially a warning that GC took a long time. Take a look at hte erlang docs for more info on the specifics of long_gc [1].
As far as preventing them, you have two options: use less memory, or increase the memory settings in your app.config to a point where Riak doesn't complain any more. Hope that helps. Mark [1] http://www.snookles.com/erlang-docs/R14B04//erts-5.8.5/doc/html/erlang.html#system_monitor-2 On Mon, Feb 6, 2012 at 3:17 AM, Gal Barnea <[email protected]> wrote: > Hi guys > we are running a relatively big map reduce (covers around 20-30 millions > records) and I'm seeing a lot of these in the logs: > ... > 2012-02-06 11:14:57.631 [info] > <0.5703.3625>@riak_core_sysmon_handler:handle_event:85 monitor long_gc > <0.2086.3871> [{initial_call,{erlang,apply,2}},{almost_ > current_function,{gen,do_call,4}}] > [{timeout,253},{old_heap_block_size,0},{heap_block_size,59786060},{mbuf_size,0},{stack_size,17},{old_heap_size,0},{heap_si > ze,17553801}] > 2012-02-06 11:14:57.632 [info] > <0.5703.3625>@riak_core_sysmon_handler:handle_event:85 monitor large_heap > <0.2086.3871> [{initial_call,{erlang,apply,2}},{almo > st_current_function,{gen,do_call,4}}] > [{old_heap_block_size,0},{heap_block_size,59786060},{mbuf_size,0},{stack_size,17},{old_heap_size,0},{heap_size,17553801 > }] > 2012-02-06 11:15:10.995 [info] > <0.5703.3625>@riak_core_sysmon_handler:handle_event:85 monitor long_gc > <0.2086.3871> [{initial_call,{erlang,apply,2}},{almost_ > current_function,{gen,do_call,4}}] > [{timeout,240},{old_heap_block_size,0},{heap_block_size,59786060},{mbuf_size,0},{stack_size,17},{old_heap_size,0},{heap_si > ze,17479047}] > 2012-02-06 11:15:10.995 [info] > <0.5703.3625>@riak_core_sysmon_handler:handle_event:85 monitor large_heap > <0.2086.3871> [{initial_call,{erlang,apply,2}},{almo > st_current_function,{gen,do_call,4}}] > [{old_heap_block_size,0},{heap_block_size,59786060},{mbuf_size,0},{stack_size,17},{old_heap_size,0},{heap_size,17479047 > }] > > This is probably harmless being logged as INFO, however, seeing a lot of > these, I would be glad to understand why these are happening and what I can > do to prevent them? > > Thanks > Gal > > _______________________________________________ > riak-users mailing list > [email protected] > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > >
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