Why would this singleton occasionally crash when invoked from DllMain?

Invoking a singleton instance from the DllMain function can be problematic and may lead to crashes or undefined behavior. This is because the DllMain function is called by the system during various initialization and termination events, and it imposes certain restrictions and limitations.

One of the main issues with invoking a singleton instance from DllMain is that it runs under the loader lock, which means that the execution of the DllMain function can be serialized and blocked by other threads. This can cause deadlocks or issues if the singleton initialization relies on other modules or resources that may also be locked or unavailable at the time DllMain is called.

It is generally recommended to keep the DllMain function as minimal and straightforward as possible. Complex or time-consuming operations, such as instantiating singletons or acquiring locks, should be avoided within DllMain. Instead, consider deferring such operations to a later stage when the DLL is already loaded and initialized.

If you need to use a singleton instance in a DLL, it is recommended to initialize it lazily or on-demand, preferably outside of the DllMain function. This allows you to control the initialization flow and avoid potential issues associated with the loader lock.

If you provide more specific details about the crash or the code in question, I may be able to provide more targeted advice.