Hello to everybody:
Some time ago i posted about some strange problems I had with replications
that lead to a hanged up database.
Unluckily the problem was difficult to reproduce, and none of the
suggestion I got here managed to exactly catch the problem.
After may tries, now I've concluded that replication was a red herring...
the problems seems to be views.
Sometimes they hang.
The only error I always get is that unhelpful message of timeout...
debug] [<0.25571.67>] OS Process Start :: #Port<0.23218>
[debug] [<0.25571.67>] OS Process #Port<0.23218> Input ::
["reset",{"reduce_limit":true,"timeout":60000}]
[error] [<0.24826.67>] OS Process Error <0.25564.67> :: {os_process_error,
"OS process timed
out."}
I've to point that the 60000 come from an attempt to increase the timeout
limit, but I get thousands of these lines one each few seconds, exactly the
same as I left the 5000 default.
After may attempts, it does terminate with an error report of this kind:
=ERROR REPORT==== 1-Nov-2015::15:23:12 ===
Error in process <0.21125.16> with exit value:
{{nocatch,{os_process_error,"OS process timed
out."}},[{couch_os_process,prompt,2,[{file,"couch_os_process.erl"},{line,57}]},{couch_query_servers,map_doc_raw,2,[{file,"couch_query_servers.erl"},{line,88}]},{couch_mrview_updater...
[debug] [<0.21021.16>] Minor error in HTTP request: {os_process_error,
"OS process timed
out."}
[debug] [<0.21021.16>] Stacktrace: [{couch_mrview_util,get_view,4,
[{file,"src/couch_mrview_util.erl"},
{line,49}]},
{couch_mrview,query_view,6,
[{file,"src/couch_mrview.erl"},
{line,75}]},
{couch_httpd,etag_maybe,2,
[{file,"couch_httpd.erl"},{line,610}]},
{couch_mrview_http,design_doc_view,5,
[{file,"src/couch_mrview_http.erl"},
{line,188}]},
{couch_httpd_db,do_db_req,2,
[{file,"couch_httpd_db.erl"},{line,234}]},
{couch_httpd,handle_request_int,5,
[{file,"couch_httpd.erl"},{line,318}]},
{mochiweb_http,headers,5,
[{file,"mochiweb_http.erl"},{line,94}]},
{proc_lib,init_p_do_apply,3,
[{file,"proc_lib.erl"},{line,237}]}]
[info] [<0.21021.16>] x.x.x.x - - GET /bozze/_design/libri/_view/autori 500
[error] [<0.21021.16>] httpd 500 error response:
{"error":"os_process_error","reason":"OS process timed out."}
The views that hang are really simple, they only check if a couple of
fields are present and then emit a few fields for all the records that have
them..
The record themselves are relatively tame, I tried access them one by one
with an external script and executing externally the same code of the view,
and all that take less than 3 seconds, json decoding included.
The machine itself have plenty of spare RAM and the load while the db is
hanged is very low, less than 1.
The really frustrating thing is that there isn't anything pointing me to
what could be wrong, if it's something I'm causing, a bug, or whatever, and
it's making me reconsider the idea of using this product: other db systems
too have their own quirks, but usually when they have something wrong, be
their fault or the user, it's quite clear where the problem is... here it's
all fog.
I can understand that this is less of a problems for people that have a lot
of experience with the product and its inner working, but for a more
widespread use that could be a deal-breaker, nothwithstanding all the cool
features...
I'd love to be able to point to a test-case to reproduce the bug in a
consistent manner, but all my attempts to pinpoint a cause for this
behaviour failed: the system always hang only with real-world data, in a
non predicable way... and as it does not point to a specific record causing
the malfunction, I'm left incapable of finding what's causing the problem...
If somebody have some suggestions, I'm otherwise at the end of what I can
think of..
--
Francesco Zamboni
tel: +39 0522 1590100
fax: +39 0522 331673
mob: +39 335 7548422
e-mail: [email protected] <[email protected]>
web: www.mastertraining.it
Sede Legale: via Timolini, 18 - Correggio (RE) - Italy
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