test

Oracle Solaris Studio 12.2：线程分析器用户指南

3.5.2 检查存在潜在死锁但仍可完成的运行

如果提供足够大的休眠参数，哲学家就餐程序就可避免实际死锁并正常终止。但是，正常终止并不意味着程序可以完全避免死锁。它仅仅表示在给定的一次运行中，持有和请求的锁未形成死锁链。如果在其他运行中出现了时间变化，则仍可能会发生实际死锁。下面列出了由于引入 40 秒休眠时间而正常终止的哲学家就餐程序的一次运行。但是，er_print 实用程序和线程分析器会报告潜在死锁。


% cc -g -o din_philo_pt din_philo.c
% collect -r deadlock -o din_philo_pt.1.er din_philo_pt 40
Creating experiment database tha.2.er ...
Philosopher 0 is done thinking and now ready to eat.
Philosopher 2 is done thinking and now ready to eat.
Philosopher 1 is done thinking and now ready to eat.
Philosopher 3 is done thinking and now ready to eat.
Philosopher 2: got right  chopstick 2
Philosopher 3: got right  chopstick 3
Philosopher 0: got right  chopstick 0
Philosopher 4 is done thinking and now ready to eat.
Philosopher 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 3: got left chopstick 4
Philosopher 3: eating.
Philosopher 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 0: got right  chopstick 0
Philosopher 2: got left chopstick 3
Philosopher 2: eating.
...
Philosopher 4: got right  chopstick 4
Philosopher 3: got right  chopstick 3
Philosopher 2: got right  chopstick 2
Philosopher 4: got left chopstick 0
Philosopher 4: eating.
Philosopher 4 is done eating.
Philosopher 3: got left chopstick 4
Philosopher 3: eating.
Philosopher 0: got right  chopstick 0
Philosopher 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 3 is done eating.
Philosopher 2: got left chopstick 3
Philosopher 2: eating.
Philosopher 0 is done eating.
Philosopher 2 is done eating.
Philosopher 1: got right  chopstick 1
Philosopher 1: got left chopstick 2
Philosopher 1: eating.
Philosopher 1 is done eating.
%

Execution terminated normally

键入下列以粗体显示的命令以使用 er_print 实用程序检查实验：


% er_print din_philo_pt.1.er
(er_print) deadlocks
Deadlock #1, Potential deadlock
  Thread #2
    Lock being held:      0x215a0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215b8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #3
    Lock being held:      0x215b8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215d0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #4
    Lock being held:      0x215d0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215e8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #5
    Lock being held:      0x215e8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x21600, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #6
    Lock being held:      0x21600, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215a0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"

Deadlocks List Summary: Experiment: din_philo_pt.1.er Total Deadlocks: 1
(er_print)
 
Deadlock #1, Potential deadlock
  Thread #2
    Lock being held:      0x215a0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215b8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #3
    Lock being held:      0x215b8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215d0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #4
    Lock being held:      0x215d0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215e8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #5
    Lock being held:      0x215e8, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x21600, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
  Thread #6
    Lock being held:      0x21600, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"
    Lock being requested: 0x215a0, at: grab_chopstick + 0x0000002C, line 106 in "din_philo.c"

Deadlocks List Summary: Experiment: din_philo_pt.1.er Total Deadlocks: 1
(er_print)

以下屏幕抓图显示了线程分析器界面中的潜在死锁信息。

图 3–4 din_philo.c 中的潜在死锁

线程分析器窗口的屏幕抓图，显示了潜在的死锁。