[elephant-devel] multithreading

[Ian Eslick]

Actually these days it's quite easy.  If you have a function that  
acts as a handler for, say, a url request and can be invoked in  
different threads all you need to do is:

All threads share a single, open store-controller object.
Each transaction is started and committed/aborted in the same thread.

The first one is easy, just use a global variable and open the store  
controller when the program starts up:

(defvar *my-db-spec* '(:BDB "/user/me/db/"))
(defvar *my-db-store* nil)

(defun startup ()
   (setf *my-db-store* (open-store *my-db-spec*)))

Then a good policy to avoid transactions across threads is:
1) Always use with-transaction
2) Never spawn a thread from within the dynamic extent of the with- 
transaction body form(s)

Pretty simple!

I'm sorry we don't have a good canned example, however I've attached  
a hutchentoot-based blog example that is current and that I believe  
would run fine in multiple threads, although I haven't tested it.

Regards,
Ian

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On May 16, 2007, at 4:27 AM, Dmitry V. Gorbatovsky wrote:

> Hello and thanks for glorious project.
> I would like to ask for very short (few lines) example
> of using 'elephant' in multiple threads on sbcl/linux.
> Or maybe just link to where I may find one.
>
> Beforehand gratefull.
> Dmitry
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