下面列出了导致实际死锁的哲学家就餐程序的一次运行。
% cc -g -o din_philo din_philo.c % collect -r deadlock -o din_philo.1.er din_philo Creating experiment database din_philo.1.er ... Philosopher 1 is done thinking and now ready to eat. Philosopher 2 is done thinking and now ready to eat. Philosopher 3 is done thinking and now ready to eat. Philosopher 0 is done thinking and now ready to eat. Philosopher 1: got right chopstick 1 Philosopher 3: got right chopstick 3 Philosopher 0: got right chopstick 0 Philosopher 1: got left chopstick 2 Philosopher 3: got left chopstick 4 Philosopher 4 is done thinking and now ready to eat. Philosopher 1: eating. Philosopher 3: eating. Philosopher 3: got right chopstick 3 Philosopher 4: got right chopstick 4 Philosopher 2: got right chopstick 2 Philosopher 0: got left chopstick 1 Philosopher 0: eating. Philosopher 1: got right chopstick 1 Philosopher 4: got left chopstick 0 Philosopher 4: eating. Philosopher 0: got right chopstick 0 Philosopher 3: got left chopstick 4 Philosopher 3: eating. Philosopher 4: got right chopstick 4 Philosopher 2: got left chopstick 3 Philosopher 2: eating. Philosopher 3: got right chopstick 3 Philosopher 1: got left chopstick 2 Philosopher 1: eating. Philosopher 2: got right chopstick 2 Philosopher 0: got left chopstick 1 Philosopher 0: eating. Philosopher 1: got right chopstick 1 Philosopher 4: got left chopstick 0 Philosopher 4: eating. Philosopher 0: got right chopstick 0 Philosopher 3: got left chopstick 4 Philosopher 3: eating. ... Philosopher 4: got right chopstick 4 Philosopher 2: got left chopstick 3 Philosopher 2: eating. Philosopher 2: got right chopstick 2 Philosopher 3: got right chopstick 3 (hang) Execution terminated by pressing CTRL-C |
键入以下命令以使用 er_print 实用程序检查实验:
% er_print din_philo.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" Deadlock #2, Actual 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.1.er Total Deadlocks: 2 (er_print)
以下屏幕抓图显示了线程分析器中显示的死锁信息。
线程分析器报告了 din_philo.c 的两个死锁,一个是潜在死锁,另一个是实际死锁。通过进一步检查,可以发现两个死锁是相同的。
该死锁涉及的循环链如下:
线程 2:在地址 |
线程 3:在地址 |
线程 4:在地址 |
线程 5:在地址 |
线程 6:在地址 |
选择循环链中的第一个线程(线程 2),然后单击 "Dual Source"(双源)标签,可以在源代码中看到,线程 2 在地址 0x215a0
持有锁,在源代码中也可以看到,该线程在地址 0x215b8
请求锁。以下屏幕抓图显示了对应于线程 2 的 "Dual Source"(双源)标签。每个源代码行的左侧会显示缺省的度量:"Exclusive Deadlocks"(互斥死锁)度量。此度量显示了该行上报告的(死锁涉及的)锁持有或锁请求操作的总次数。