| Abstract: | This paper reports on an experimental study of the probe effect, defined as an alteration in the frequency of run-time computational errors observed when delays are introduced into concurrent programs. If the concurrent program being studied has no synchronization errors, then there is no probe effect. In the presence of synchronization errors, the frequency of observable output errors for a sample experimental program starts at a high value for small delays, oscillates rapidly as the delay is increased, and apparently settles at zero errors for larger values of delay. Thus, for sufficiently large delays, the probe effect can almost completely mask synchronization errors in concurrent programs. For sufficiently large concurrent process sets, even small values of embedded delay may mask synchronization errors, provided side effects in shared memory are not included in the observation. |
