Drupal stops logging after some time

Problem/Motivation

I noticed that after some time Drupal stops logging messages on watchdog.
Debugging the code I noticed that the variable $original_implementations is always empty when this issue happens, so watchdog is not called.

$original_implementations = &drupal_static('watchdogalter_original_implementations', array());
foreach (array_keys($original_implementations) as $module) {
  module_invoke($module, 'watchdog', $log_entry);
}

Proposed resolution

I suggest to use variable_set and variable_get for 'watchdogalter_original_implementations' instead of drupal_static.
variable_set and variable_get are cached and it should not affect the performance.