Apa mekanisme IPC utama, lan kapan nganggo saben siji?

Question

IT Interview Practice · Accepted Answer

Amarga saben proses duwe **ruang alamat sing dipisah**, dheweke ora bisa mung nganggo bareng variabel — dheweke butuh **inter-process communication (IPC)**. OS nyediakake sawetara mekanisme, beda ing kacepetan, arah, lan apa dheweke mlaku antar mesin.

## Mekanisme utama

```text
Pipe / FIFO      → byte stream, one direction; anonymous pipe = parent↔child, named FIFO = any procs
                   e.g.  ls | grep foo   (the shell wires stdout→stdin via a pipe)
Shared memory    → both map the SAME physical pages → FASTEST (no copy), but you must
                   synchronize access yourself (semaphore/mutex)
Message queue    → kernel-managed queue of discrete messages; decoupled, preserves boundaries
Socket           → bidirectional stream/datagram; UNIX-domain (same host) or TCP/UDP (across network)
Signal           → tiny async notification (a number), e.g. SIGINT, SIGTERM — control, not data transfer
```

## Milih siji

- **Pipe** — byte stream siji arah sing prasaja; balung punggung shell pipeline lan pipa parent/child.
- **Shared memory** — nalika kowe butuh **throughput dhuwur / latency endhek** (contone shared buffer database). Iki paling cepet amarga data ora dicopy liwat kernel — nanging dheweke *ora* nyediakake sinkronisasi, mula kudu dipasangi karo semaphore.
- **Message queue** — nalika kowe pengin **pesen sing kapisah** kanthi wates sing kejaga lan kopling longgar.
- **Socket** — sing paling fleksibel: **UNIX-domain socket** ing host padha iku cepet; socket TCP/UDP uga mlaku **antar mesin**, iki sebabe service jaringan nganggo dheweke.
- **Signal** — kanggo acara **kontrol** (interupsi, mungkasi, proses anak metu), dudu kanggo mindhah data.

```text
        copy through kernel                          no copy
  slower ◀─────────────────────────────────────────────▶ faster
  socket / message queue / pipe            shared memory (+ your own locking)
```

## Kenapa iki penting

Pilihan IPC mbentuk arsitektur lan performa sawijining sistem. Pewawancara pengin ndeleng kowe nyocogake mekanisme karo kabutuhan: shared memory kanggo kacepetan mentah (nampa beban sinkronisasi), socket kanggo keluwesan lan transparansi jaringan, pipe kanggo streaming prasaja, signal kanggo kontrol. Iki dhasar kanggo mangerteni kepiye shell pipeline, web server multi-proses, shared buffer database, utawa microservice tenanan ngomong siji lan sijine.

Mekanisme utama

Milih siji

Kenapa iki penting

Pitakon sing gegandhengan