[Seaside] mutual exclusion: WAProcessMonitor critical:ifError

[Bany, Michel]

> It appears especially when I launch a "complex" process when 
> rendering ("complex" is long and UI on the server (progress bars)).
> It appears when refreshing the page with the navigators'button.

Ah, this is different. If the amount of processing done by your
"complex" process is very large, then it is normal that Seaside does not
respond and the process monitor shows WAProcessMonitor>>critical:ifError
while the "complex" process is running.

In such situations, if the user gets impatient and tries the navigator's
refresh button, then a second HTTP request is sent for the same Seaside
session while the first HTTP request with the "complex" process is still
being processed. The second HTTP request is suspended by the
WAProcessMonitor
until the "complex" process is complete. Seaside is designed that way.

Rather than using the navigator's refresh button, you can also use the
"Terminate" link in the toolbar at the bottom.

HTH,
Michel.