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From Apache Wiki <wikidi...@apache.org>
Subject [Couchdb Wiki] Update of "FUQ" by RandallLeeds
Date Tue, 06 Dec 2011 18:39:55 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Couchdb Wiki" for change notification.

The "FUQ" page has been changed by RandallLeeds:
http://wiki.apache.org/couchdb/FUQ?action=diff&rev1=3&rev2=4

Comment:
More information about Erlang backtraces.

  
  == Log Files ==
   1. Those Erlang messages in the log are pretty confusing. What gives?
+    While the Erlang messages in the log can be confusing to someone unfamiliar with Erlang,
with practice they become very helpful. The CouchDB developers do try to catch and log messages
that might be useful to a system administrator in a friendly format, but occassionally a bug
or otherwise unexpected behavior manifests itself in more verbose dumps of Erlang server state.
These messages can be very useful to CouchDB developers. If you find many confusing messages
in your log, feel free to inquire about them. If they are expected, devs can work to ensure
that the message is more cleanly formatted. Otherwise, the messages may indicate a bug in
the code.
-    Erlang kindly provides us with a stack trace. In many cases, this is enough to identify
the problem. For example, OS errors are reported as tagged tuples {{{{error,enospc}}}} or
{{{{error,enoacces}}}} which respectively is "You ran out of disk space", and "CouchDB doesn't
have permission to access that resource". Most of these errors are derived from C used to
build the Erlang VM and are documented in {{{errno.h}}} and related header files. [[http://www.ibm.com/developerworks/aix/library/au-errnovariable/|IBM]]
provides a good introduction to these, and the relevant [[http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html|POSIX]]
and [[http://www.gnu.org/s/hello/manual/libc/Error-Codes.html|GNU]] and [[http://msdn.microsoft.com/en-us/library/5814770t.aspx|Microsoft
Windows]] standards will cover most cases.
+    In many cases, this is enough to identify the problem. For example, OS errors are reported
as tagged tuples {{{{error,enospc}}}} or {{{{error,enoacces}}}} which respectively is "You
ran out of disk space", and "CouchDB doesn't have permission to access that resource". Most
of these errors are derived from C used to build the Erlang VM and are documented in {{{errno.h}}}
and related header files. [[http://www.ibm.com/developerworks/aix/library/au-errnovariable/|IBM]]
provides a good introduction to these, and the relevant [[http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html|POSIX]]
and [[http://www.gnu.org/s/hello/manual/libc/Error-Codes.html|GNU]] and [[http://msdn.microsoft.com/en-us/library/5814770t.aspx|Microsoft
Windows]] standards will cover most cases.
  

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