5 ms·

How does this work? What makes mouse movement relevant to this... this is computers, not magic.

by Freestyler_3 13y ago

resonator 13y ago
It's probably running out of entropy. If windows is anything like Linux, it will use certain random events like mouse movements, keystrokes, boot time etc. to generate randomness.
- finnw 13y ago
  Probably not in this case. Windows' RNG does not block when it runs low on entropy. AFAIK only Linux does that. And the task is a database query so probably does not use the RNG. But yes, I have seen a similar case involving linux /dev/random - the user reported that outgoing emails were sometimes delayed for hours and that moving a mouse over a VNC window would sometimes speed it up. I did not believe that at first, but it was exim4 running out of entropy when generating TLS session keys. Worse, it was on a VPS with about 20 exim4 processes competing for the entropy.
InclinedPlane 13y ago
Other folks have answered. I'll try to summarize: It's an impedance mismatch, you have a long-running background operation (sql query) that is running within the context of an event driven system (a windowing GUI). In this case the problem is that the sub-system that runs the query will only receive cycles when the main thread for the app fires mouse events. This is due to poor application design, of course, though not necessarily to the extent that it may seem, sometimes this sort of thing can be a harder problem than it may seem.
Shog9 13y ago
The exact cause would be a question for (old, probably retired) members of the Excel team at MS, but bugs like this were fairly common when working with Windows apps that mixed interprocess communication with UI updates. Raymond Chen has a great example of a similar bug here: http://blogs.msdn.com/b/oldnewthing/archive/2005/02/17/375307.aspx http://blogs.msdn.com/b/oldnewthing/archive/2005/02/17/37530...

5 ms·

How does this work? What makes mouse movement relevant to this... this is computers, not magic.

by Freestyler_3 13y ago

How does this work? What makes mouse movement relevant to this... this is computers, not magic.

resonator 13y ago
It's probably running out of entropy. If windows is anything like Linux, it will use certain random events like mouse movements, keystrokes, boot time etc. to generate randomness.
- finnw 13y ago
  Probably not in this case. Windows' RNG does not block when it runs low on entropy. AFAIK only Linux does that. And the task is a database query so probably does not use the RNG. But yes, I have seen a similar case involving linux /dev/random - the user reported that outgoing emails were sometimes delayed for hours and that moving a mouse over a VNC window would sometimes speed it up. I did not believe that at first, but it was exim4 running out of entropy when generating TLS session keys. Worse, it was on a VPS with about 20 exim4 processes competing for the entropy.
InclinedPlane 13y ago
Other folks have answered. I'll try to summarize: It's an impedance mismatch, you have a long-running background operation (sql query) that is running within the context of an event driven system (a windowing GUI). In this case the problem is that the sub-system that runs the query will only receive cycles when the main thread for the app fires mouse events. This is due to poor application design, of course, though not necessarily to the extent that it may seem, sometimes this sort of thing can be a harder problem than it may seem.
Shog9 13y ago
The exact cause would be a question for (old, probably retired) members of the Excel team at MS, but bugs like this were fairly common when working with Windows apps that mixed interprocess communication with UI updates. Raymond Chen has a great example of a similar bug here: http://blogs.msdn.com/b/oldnewthing/archive/2005/02/17/375307.aspx http://blogs.msdn.com/b/oldnewthing/archive/2005/02/17/37530...