Thanks for this excellent and informative problem report. Since I do run sqlite3 and
SBCL here at home, I should be able to use your test code to reproduce the problem.
I will try to do this tonight and tomorrow morning; I doubt I willl have much information
for your before tomorrow at noon.
Looking at the stack trace you provide, it seems that this is a SQLite error, possibly
cause by Elephant, or even CLSQL, not handling transactions properly. Since I have
only minimal knowledge of SQLite, I can't say anything else yet.
Tonight I will run your test code against a postgres database as well; this may not
solve your problem but will give us some additional information.
I am a little surprised by your use of clsql:start-transaction; the normal idiom for
this is:
(with-transaction (:store-controller *store-controller*)
(loop for obj in objs
for key in keys
do (setf (get-value key bt) obj))))
(this is an example for testcollections.lisp)
Are you saying in your email that you could not use this way of doing things? The
with-transaction macro should be indpendent of the type of the store-controller.
You wrote:
As sqlite requires each thread to have it's own connection by throwing
an error if one thread tries to reuse a connection created by another
thread at least on Ubuntu Dapper. Google says that it depends on a
compile time flag for libsqlite3.
The current Elephant code has no notion of this, and I'm pretty sure it will hand the same connection
to several threads. Obviously, you could solve this problem by using mutexes to make sure that
only one thread accesses the controller, but that might be quite unpleasant for you code.
If these comments can help you provide anymore information about what your possible solutions
are, please reply so I can think about it before I begin debugging it tonight or tomorrow.
On Wed, 2006-04-19 at 18:34 +0300, Ignas Mikalajunas wrote:
Hi, I am trying to use elephant as a backend data store for my
blogging application. And have encountered some problems with it ...
As i want to only commit the transaction in cases of error and tbnl is
using throw for redirects i need to manualy open/close transactions,
but it seems (ele:start-transaction) is only designed to work with BDB
backend, so i must use (clsql:start-transaction) instead.
At the moment the wrapper around each request looks like this:
(defun common-blog-view-wrapper (function)
(ele:with-open-store (`(:sqlite3 ,(format nil "~A"
(get-config-option "database-path"))))
(let ((error nil)
(transaction nil))
(unwind-protect
(handler-bind ((error (lambda (cond)
(declare (ignore cond))
(setf error t))))
(clsql:start-transaction)
(setf transaction t)
(tbnl::string-to-octets (funcall function) :utf-8))
(when transaction
(if error
(clsql:rollback)
(clsql:commit)))))))
As sqlite requires each thread to have it's own connection by throwing
an error if one thread tries to reuse a connection created by another
thread at least on Ubuntu Dapper. Google says that it depends on a
compile time flag for libsqlite3. Everything works more or less fine ,
but when i am reloading the page multiple times in a row very fast i
am getting a traceback (attached). And can't quite grok what went
wrong ... Maybe some one who knows internals of elephant can help me
out with this, as i could not really track where could a database
connection appear in another thread.
A testcase for SBCL:
(defun test ()
(ele:with-open-store ('(:sqlite3 "/home/ignas/src/common-blog/dev.db"))))
(sb-thread:make-thread #'test) ;; a few times - works
(dotimes (i 3) (sb-thread:make-thread #'test)) ;; you get 3 tracebacks
By the way thanks for a wonderful library!
--
Ignas Mikalajūnas
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