SQL Error when creating several contacts (with employees) at the same time: Deadlock found when trying to get lock;

Hi,

So I have used node.js to create contacts https://github.com/tttp/civi-charlatan
it fires several REST requests in parallel. I always have the first few that are in error, that it mostly works but get some more errors later on. It seems to be linked with concurrency, but not 100% sure.

Anyway, that's the error I get:
(that's a pain to debug, you can't json encode in debug mode because the call trace seems to be too big)

So I have seen that deadlock either on:

UPDATE civicrm_contact contact_a,civicrm_contact contact_b\nSET contact_a.employer_id=contact_b.id, contact_a.organization_name=contact_b.organization_name\nWHERE contact_a.id =53 AND contact_b.id=55;

Seems to be from setCurrentEmployee in CRM/Contact/BAO/Contact/Utils.php, that has a todo that I don't understand

//FIXME : currently civicrm mysql_query support only single statement
//execution, though mysql 5.0 support multiple statement execution.

Or on the creation of the employer

INSERT INTO civicrm_contact (contact_type , contact_sub_type , sort_name , display_name , hash , organization_name ) VALUES ('Organization' , NULL , 'Kohler, Bruen and McCullough' , 'Kohler, Bruen and McCullough' , 'c394319089058fdb9e2611921932ec1e' , 'Kohler, Bruen and McCullough' )

I have no idea how to isolate the problem. Do you?

More a workaround than really a fix: it seems the code
1. create the individual,
2. create the organisation then
3. update the individual

Would it be a solution (and better for performance) to change the order so

1. create the organisation
set the employer_id and org name in the individual
2. create the individual