The initialize and uninitialize methods in OpenSSLInitializer uses a construct like this:

if (++_rc == 1) { ... }

_rc is a Poco::AtomicCounter.

This is insufficient since you can easily get into a situation where both uninitialize and initialize is called at the same time from multiple threads. These methods should be protected by a mutex lock to ensure proper execution.

The workaround to keep a persistent instance of this object works of course, but that just avoids triggering the race condition.