[Quantlib-dev] [ quantlib-Bugs-3441748 ] Singleton::instance is not thread-safe

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Bugs item #3441748, was opened at 2011-11-24 02:48
Message generated for change (Tracker Item Submitted) made by mortoray
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: edA-qa mort-ora-y (mortoray)
Assigned to: Nobody/Anonymous (nobody)
Summary: Singleton::instance is not thread-safe

Initial Comment:
Singleton::instance is not thread-safe in its creation of new Sessions. There is no lock around the access to std::map and thus two threads creating a new session at the same time will conflict. This is a case that actually happens in our code: we manage to get two cores started in their processing at the same time and thus both attempt to create a session at the same time. They do this by having the sessionId return a different key per thread.

There is no way for the end-user to make this function thread-safe as any thread can request the session at any time. This actually makes QuantLib as a whole not thread-safe then, simply because you cannot safely obtain a per-thread session.

The instance() method needs to have a read-write lock so that it works correctly even when creating new sessions.

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You can respond by visiting: 
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