Сколько идентификаторов может быть открыто одновременно?
45-54 Обычно есть системное ограничение на количество одновременно открытых идентификаторов. Оно определяется непосредственно созданием очередей до тех пор, пока не произойдет ошибка при вызове msgget.
Запустим эту программу сначала в Solaris 2.6, а затем в Digital Unix 4.0B, и результаты подтвердят приведенные в табл. 6.2 величины:
solaris % limits
maximum amount of data per message = 2048
40 8-byte messages were placed on queue, 320 bytes total
40 16-byte messages were placed on queue, 640 bytes total
40 32-byte messages were placed on queue, 1280 bytes total
40 64-byte messages were placed on queue, 2560 bytes total
32 128-byte messages were placed on queue, 4096 bytes total
16 256-byte messages were placed on queue, 4096 bytes total
8 512-byte messages were placed on queue, 4096 bytes total
4 1024-byte messages were placed on queue, 4096 bytes total
2 2048-byte messages were placed on queue, 4096 bytes total
50 identifiers open at once
alpha % limits
maximum amount of data per message = 8192
40 8-byte messages were placed on queue, 320 bytes total
40 16-byte messages were placed on queue, 640 bytes total
40 32-byte messages were placed on queue, 1280 bytes total
40 64-byte messages were placed on queue, 2560 bytes total
40 128-byte messages were placed on queue, 5120 bytes total
40 256-byte messages were placed on queue, 10240 bytes total
32 512-byte messages were placed on queue, 16384 bytes total
16 1024-byte messages were placed on queue, 16384 bytes total
8 2048-byte messages were placed on queue, 16384 bytes total
4 4096-byte messages were placed on queue, 16384 bytes total
2 8192-byte messages were placed on queue, 16384 bytes total
63 identifiers at once
Причина, по которой в Digital Unix 4.0В получился результат 63 идентификатора, а не 64, как в табл. 6.2, заключается в том, что один идентификатор всегда используется системным демоном.