Linuxda semaforlarga kirish

Maqolaning tarjimasi kurs boshlanishi arafasida tayyorlangan "Administrator Linux.Basic".

Semafor - bu raqobatdosh jarayonlar va oqimlarning umumiy resurslar bilan ishlashiga imkon beruvchi mexanizm bo'lib, poygalar, blokirovkalar va ipning noto'g'ri harakati kabi turli xil sinxronlash muammolarini hal qilishda yordam beradi.

Ushbu muammolarni hal qilish uchun yadroda mutekslar, semaforlar, signallar va to'siqlar kabi vositalar mavjud.

Semaforlarning uch turi mavjud:

1. Ikkilik semafor
2. Semaforni sanash
3. Semafor massivlari (semafor to'plami)

IPC holatini ko'rish

Jarayonlararo aloqaning (IPC) joriy holati haqida ma'lumot olish uchun quyidagi buyruqlardan foydalanish mumkin.

# 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

Faol semafor massivlari

Faol semafor massivlari haqidagi ma'lumotlarni ko'rsatish.

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

Umumiy xotira segmentlari

Faol umumiy xotira segmentlari haqidagi ma'lumotlarni ko'rish.

# 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

Cheklovlar

komanda ipcs -l umumiy xotira, semafor va xabar chegaralarini ko'rsatadi.

# 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

Umumiy xotira

Quyidagi buyruq umumiy xotirani ko'rsatadi.

# 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

Resurs yaratuvchilari

Buyruq foydalanuvchi va resurs egasi va yaratuvchisining guruhini ko'rsatadi.

# 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

IPC vositalaridan foydalanish

Quyidagi misolda parametr -u Barcha IPC vositalaridan foydalanishning qisqacha mazmunini ko'rsatadi.

# 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

Xizmatlar to'xtatilganda, semaforlar va umumiy xotira segmentlari ham o'chirilishi kerak. Agar ular o'chirilmasa, bu IPC ob'ekt identifikatoridan o'tib, ipcrm buyrug'i yordamida amalga oshirilishi mumkin.

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

Bundan tashqari, yordamida semafor chegaralarini o'zgartirishingiz mumkin sysctl.

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

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