Straggler
A single task that runs far longer than its peers and holds up completion of the whole run.
A run finishes when its slowest partition finishes, so one oversized piece of work erases the benefit of splitting the rest evenly. Uneven partitions are the usual cause, not slow hardware.
Performance & optimizationDistributed compute
Related terms
- Long tail: The situation where most tasks finish quickly but one or two run much longer, so the whole run waits on them while workers sit idle.
- Partition: One independently processable chunk of a dataset. Partition size is the main lever on how well a workload parallelizes.