Wrong behavior when another processes finishes on other devices

[tiermak]

Let's image there are 4 GPUs on a node.

1. Some other process uses GPUs 0 and 1;
2. A process with cuq starts using GPUs 2 and 3;
3. Process (1) finishes;
4. On a new call of processTasks process (2) occupies GPUs 0 and 1, and doesn't release GPUs 2 and 3.