Bubuka pikeun Semaphores dina Linux

Tarjamahan tina artikel ieu disiapkeun dina wengi mimiti kursus "Administrator Linux.Dasar".

Semafor mangrupikeun mékanisme anu ngamungkinkeun prosés sareng benang bersaing pikeun ngabagi sumber daya sareng ngabantosan sagala rupa masalah sinkronisasi sapertos balapan, jalan buntu (silih konci), sareng benang anu salah.

Pikeun ngajawab masalah ieu, kernel nyadiakeun parabot kayaning mutexes, semaphores, sinyal, sarta halangan.

Aya tilu jinis semaphore:

1. semaphore binér
2. Semaphores-counters (ngitung semafor)
3. Array of semaphores (set semaphore)

Nempo Status IPC

Paréntah di handap ieu nyayogikeun inpormasi ngeunaan kaayaan ayeuna komunikasi antar-prosés (IPC).

# ipcs
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest
------ Semaphore Arrays --------

key semid owner perms nsems

------ Message Queues --------
key msqid owner perms used-bytes messages

Asép Sunandar Sunarya aktif semaphores

Témbongkeun informasi ngeunaan arrays semafor aktip.

# ipcs -s
------ Semaphore Arrays --------
key semid owner perms nsems

Bagéan mémori dibagikeun

Tempo inpo ngeunaan bagéan mémori dibagikeun aktip.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest

Watesan

regu ipcs -l mintonkeun memori dibagikeun, semaphore, jeung wates pesen.

# ipcs -l
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 4194303
max total shared memory (kbytes) = 1073741824
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

------ Messages: Limits --------
max queues system wide = 16
max size of message (bytes) = 65536
default max size of queue (bytes) = 65536

memori dibagikeun

Paréntah di handap mintonkeun memori dibagikeun.

# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 65536 root 600 393216 2 dest
0x00000000 98305 root 600 393216 2 dest
0x00000000 131074 root 600 393216 2 dest
0x00000000 163843 root 600 393216 2 dest
0x00000000 196612 root 600 393216 2 dest
0x00000000 229381 root 600 393216 2 dest
0x00000000 262150 root 600 393216 2 dest
0x00000000 294919 root 600 393216 2 dest
0x00000000 327688 root 600 393216 2 dest

Panyipta Sumberdaya

Paréntah nampilkeun pangguna sareng grup anu gaduh sareng panyipta sumberdaya.

# ipcs -m -c

------ Shared Memory Segment Creators/Owners --------
shmid perms cuid cgid uid gid
65536 600 root root root root
98305 600 root root root root
131074 600 root root root root
163843 600 root root root root
196612 600 root root root root
229381 600 root root root root
262150 600 root root root root
294919 600 root root root root
327688 600 root root root root

Ngagunakeun parabot IPC

Dina conto di handap, parameter -u mintonkeun kasimpulan pamakean sadaya parabot IPC.

# ipcs -u

------ Shared Memory Status --------
segments allocated 9
pages allocated 864
pages resident 477
pages swapped 0
Swap performance: 0 attempts 0 successes

------ Semaphore Status --------
used arrays = 0
allocated semaphores = 0

------ Messages: Status --------
allocated queues = 0
used headers = 0
used space = 0 bytes

Nalika jasa dieureunkeun, semaphore sareng bagéan mémori anu dibagikeun ogé kedah dihapus. Upami aranjeunna henteu dipiceun, maka ieu tiasa dilakukeun nganggo paréntah ipcrm, ngalangkungan identifier objék IPC.

# ipcs -a
# ipcrm -s < sem id>

Anjeun oge bisa ngarobah wates semafor ngagunakeun sysctl.

# /sbin/sysctl -w kernel.sem=250

sumber: www.habr.com