test

Sun Studio 12：线程分析器用户指南

3.4 了解实验结果

本部分将详细说明如何使用线程分析器来检查哲人进餐程序中的死锁。首先将执行导致实际死锁的运行，然后将检查正常终止但有潜在死锁的运行。

3.4.1 检查出现死锁的运行

以下列表显示了导致实际死锁的哲人进餐程序的一个运行。

prompt% cc din_philo.c -mt -g             

prompt% collect -r deadlock a.out
Creating experiment database tha.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 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


% er_print tha.1.er 
(er_print) deadlocks

Deadlock #1, Potential deadlock
	Thread #2
		Lock being held:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #3
		Lock being held:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #4
		Lock being held:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #5
		Lock being held:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #6
		Lock being held:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"

Deadlock #2, Actual deadlock
	Thread #2
		Lock being held:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #3
		Lock being held:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #4
		Lock being held:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #5
		Lock being held:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #6
		Lock being held:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"

Deadlocks List Summary: Experiment: tha.1.er Total Deadlocks: 2
(er_print)

下面的屏幕抓图给出了线程分析器中显示的死锁信息：

显示实际死锁的线程分析器窗口屏幕抓图。

线程分析器报告了 din_philo.c 的两个死锁，一个潜在死锁和一个实际死锁。通过进一步地检查，我们发现这两个死锁是相同的。死锁中涉及的循环链如下：

线程 2： 

在地址 0x215a8 占用锁，在地址 0x215c0 请求锁

线程 3： 

在地址 0x215c0 占用锁，在地址 0x215d8 请求锁

线程 4： 

在地址 0x215d8 占用锁，在地址 0x215f0 请求锁

线程 5： 

在地址 0x215f0 占用锁，在地址 0x21608 请求锁

线程 6： 

在地址 0x21608 占用锁 ，在地址 0x215a8 请求锁

选择链中的第一个线程（线程 #2），然后单击“双重数据源”选项卡，查看在源代码中的何处，线程 #2 占用锁（在地址 0x215a8），以及在何处请求锁（在地址 0x215c0）。以下屏幕抓图显示了 2 号线程的“双重数据源”选项卡。在每个源代码行的左侧显示了缺省度量（互斥死锁度量）。该度量提供（死锁中所涉及的）锁定占用或锁定请求操作在该代码行上报告的次数。

显示潜在死锁的线程分析器“双重数据源”选项卡屏幕抓图。

3.4.2 检查存在潜在死锁但仍可完成的运行

在提供足够大的休眠参数时，哲人进餐程序可避免实际死锁，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。它仅仅表示在一次特定的运行中，占用和请求的锁定不会构成死锁链。如果在其他运行中计时发生更改，则还会发生实际死锁。以下列表显示了正常终止的哲人进餐程序的一次运行。但是 er_print 实用程序和线程分析器会报告潜在死锁。

% cc din_philo.c -mt -g                


% collect -r deadlock a.out 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 right  chopstick 0
Philosopher 4: got right  chopstick 4
Philosopher 2: got left chopstick 3
Philosopher 2: eating.
Philosopher 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 3: got right  chopstick 3
Philosopher 2: got right  chopstick 2
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 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 4: got right  chopstick 4
Philosopher 2: got left chopstick 3
Philosopher 2: eating.
Philosopher 4: got left chopstick 0
Philosopher 4: eating.
Philosopher 3: got right  chopstick 3
Philosopher 2: got right  chopstick 2
Philosopher 0: got right  chopstick 0
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 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 4: got right  chopstick 4
Philosopher 3: got right  chopstick 3
Philosopher 4: got left chopstick 0
Philosopher 4: eating.
Philosopher 0: got right  chopstick 0
Philosopher 3: got left chopstick 4
Philosopher 0: got left chopstick 1
Philosopher 0: eating.
Philosopher 3: eating.
Philosopher 0: got right  chopstick 0
Philosopher 2: got left chopstick 3
Philosopher 2: eating.
Philosopher 0: got left chopstick 1
Philosopher 0: 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


% er_print tha.2.er 
(er_print) deadlocks

Deadlock #1, Potential deadlock
	Thread #2
		Lock being held:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #3
		Lock being held:	0x215c0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #4
		Lock being held:	0x215d8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #5
		Lock being held:	0x215f0, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
	Thread #6
		Lock being held:	0x21608, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"
		Lock being requested:	0x215a8, at: grab_chopstick + 0x0000002C, line 101 in "din_philo.c"

Deadlocks List Summary: Experiment: tha.2.er Total Deadlocks: 1
(er_print)

下面的屏幕抓图显示了线程分析器界面的潜在死锁信息：

显示潜在死锁的线程分析器窗口屏幕抓图。