Search the practice set
126 questions, 454 terms and 400 topics in 20 areas.
9 results for “Concurrency”
Concurrency
The number of operations in progress at once — distinct from parallelism, which is how many are literally executing simultaneously.
Optimistic Concurrency Control
Allowing concurrent work without locks and detecting conflict at write time by checking that the underlying version has not changed.
Connection Pool
A fixed set of reusable database connections shared by an application's requests, and one of the most common hidden capacity ceilings.
Little's Law
In a stable system, the average number of items in it equals the arrival rate times the average time each spends in it — L = λW.
Message Ordering
The guarantee about the sequence in which messages are delivered — normally per-partition or per-group only, and lost the moment consumption is parallelised.
Thread Pool Isolation
Giving each downstream dependency its own pool of threads or permits, so one slow dependency cannot consume the capacity needed to serve everything else.
Two-Phase Locking
The concurrency control protocol behind serializable isolation — acquire locks in a growing phase, release only in a shrinking phase, never interleaving the two.
WhatsApp's Small-Team Scale
WhatsApp served hundreds of millions of users with a few dozen engineers by matching one technology choice precisely to the workload and refusing to add anything else.