CN105786703B9 - A kind of deadlock self-repairing method obtained in advance based on lock - Google Patents
A kind of deadlock self-repairing method obtained in advance based on lock Download PDFInfo
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Abstract
The present invention relates to a kind of deadlock self-repairing method obtained in advance based on lock, belong to software test field and software reliability field, step includes：Control flow chart first in the synchronization module and synchronization module of extraction procedure, calculates the set of the operation in synchronization module to other locks；Then suitable candidate threads are selected to perform deadlock reparation operation：If be related in the thread of deadlock, there are a thread, and there is no the operation to other locks between the operation of two of which acquisition lock, then, lock is directly performed to the thread, and acquisition operates in advance, carries out deadlock reparation；Otherwise, the control of context-aware conditions is added on the basis of performing lock and obtaining operation in advance, carries out deadlock reparation.The present invention removes the deadlock in repair procedure in the case where not introducing new lock.In theory it can be proved that the present invention will not introduce new deadlock, new deadlock is not introduced during 20 deadlocks are successfully repaired, and serious performance will not be caused to reduce problem.
Description
Technical field
The invention belongs to software testing technology field and software reliability field, and more particularly to deadlock is repaired automatically in multithread programs
Method.
Background technology
With widely using for multi-core CPU, it is certain concomitantly to handle that more and more softwares have used multithreading
Task.But multithread programs need each thread synchronously to complete some task well in the process of running.When
When synchronous appearance between these threads is wrong, the generation of concurrent defect is may result in, deadlock (Deadlock) is exactly most
A kind of basic concurrent defect.
Deadlock is commonly divided into resource deadlock (resource deadlock) and communication deadlock (communication deadlock)
Two major classes, communication deadlock are often as the Buffer competition sent and received to information and produce；Resource deadlock, i.e., two
A or more than two threads are when concurrently performing, since the resource for each needing to ask is by other lines in them
Cheng Zhanyou, causes mutually to wait, the state that can not be continued to run with.Present invention is generally directed to the reparation of resource deadlock.Mainstream
Deadlock recovery technique, mostly transported by the new lock of static or dynamic insertion to serialize the thread in concurrence error
OK, so as to repair deadlock (these repair modes are referred to as GA).Although such repair mode is very simple,
During reparation, new deadlock is easily introduced；And the side of deadlock is repaired in this serialization using between thread
Formula, it is most likely that reduce performance and efficiency that program performs.Grail (FSE 2014) is also by adding one in outer layer
It is new to lock to carry out deadlock reparation, unlike, the new lock of Grail additions is not static state, but with deadlock occurs
Object lock is related.Grail reduces the performance issue repaired and brought to a certain extent, but can still introduce new deadlock.
Therefore, by static state or dynamically, in outer layer addition, newly lock is not optimal deadlock restorative procedure.
The content of the invention
The technology of the present invention solves the problems, such as：A kind of deadlock obtained in advance based on lock is overcome the deficiencies of the prior art and provide to repair automatically
Method (automatic reparation of the present invention for resource deadlock), is not introducing new deadlock (including resource deadlock and communication deadlock)
On the premise of, all deadlocks are successfully repaired, and test and show, automatic repair of the invention will not be caused under serious performance
Drop problem.
The technology of the present invention solution：A kind of deadlock self-repairing method DFixer obtained in advance based on lock, by extracting deadlock
The synchronization module and control flow of relevant thread, calculate in each synchronization module to the operational set of other locks, select suitable time
Route selection journey, performs lock and obtains operation in advance, in the case where avoiding adding new lock, successfully repairs all deadlocks, and avoid drawing
Enter new deadlock (resource deadlock and communication deadlock), comprise the following steps：
(1) a deadlock D in preset sequence P and P, for the per thread in deadlock D, is searched for using DFS
Automatically extract deadlock D occur when D in each thread function call information, the information include D in per thread be as
What reaches deadlock point；The function call information may also require that user specifies；Based on this information, in the D of calculation procedure
Control flow chart CFG in the synchronization module and synchronization module of per thread, wherein synchronization module refer to each in D
The relevant part obtained twice between lock operation of thread deadlock, the object lock that this in per thread is locked to operation twice are taken
Following mark：First is denoted as h locks, and second is denoted as w locks；
(2) calculate synchronization module in other lock operation set, the operation include to lock acquisition operation, etc. it is to be operated
Wait and notice operation Notify；
(3) according to the set obtained in step (2), suitable candidate threads are selected to perform deadlock reparation from deadlock D
Operation：If be related in the thread of deadlock, there are a thread, it is relevant deadlock to obtain between lock operation not twice
In the presence of the operation to other locks, second lock w of the directly deadlock relevant operation to the thread performs lock and obtains behaviour in advance
Make, and the operation before deletion to second lock w, carry out deadlock reparation；
(4) if not having thread to be selected in step (3), other threads are chosen, it meets that lock obtains twice in the thread
Minimum thread is operated to other locks between extract operation, performs and acquisition operation in advance is locked described in step (3), it is in addition attached
Add context-aware conditions to control, according to the lock action type between lock h operations and lock w operations, there is following A and B
Two kinds of situations：
A：If wherein there is the acquisition operation to other locks, it is p to remember the lock, then before the acquisition to locking p, addition
Variable vhw, which determines that the value for setting knots modification be true by locking w and h, discharges lock w afterwards, and change original
To be retrieved as operating to obtaining while lock p and w to p, variable v is set afterwardshwValue be false；
B：If wherein exist to other locks etc. to be operated or notice operate, remember that the lock is locked for k, then to locking k
Before acquisition, variable v is addedhw, the variable by lock w and h determine that the value for setting the variable is true, is discharged afterwards
Lock w, and originally to lock k etc. it is to be operated after addition to lock k release operate, and to lock k and lock w it is same
When obtain operation, variable v is set afterwardshwValue be false；
(5) after the operation of step (3) or (4), repair the program destroyed because of obtaining in advance for w of lock and patrol
Volume；
(6) program after being repaired in step (3) or step (4) is denoted as P'；
(7) in addition the program P' after execution is repaired, if compiling failure, returns to (3), selects from deadlock D
Candidate threads, deadlock reparation is carried out according to the restorative procedure in step (3) and (4)；If the time that can not select
Route selection journey, then can not repair the deadlock；
In the step (1), using the function call information of each thread in D during the extraction D generations of DFS searching algorithms.
In the step (3), selected from deadlock D the standard of suitable candidate line for：To other locks in synchronization module
The minimum thread of operation amount.
In the step (3), what second was locked is retrieved as in advance：Obtained together with first lock in the thread,
Exploratory acquisition operation tryAcq based on lock, can return to whether a lock can be instantly captured at once, if two locks
It cannot at the same time obtain, then release immediately the lock wherein obtained, and be attempted next time, until two locks are same
When obtain；Synchronous two locks of acquisition are realized using tryAcq, avoid introducing new lock order relation.
In the step (5), the programmed logic destroyed because of obtaining in advance for w of lock is repaired just：According to step (3)
Or the thread chosen in (4) is in the operation and step (1) extraction before lock w is obtained in advance to two lock h and w
The relation of stream is controlled, there are following five kinds of basic conditions of A, B, C, D, E：
A single entry single exits：Acquisition operation to lock h necessarily causes to operate the acquisition for locking w, and obtains behaviour to lock w
The acquisition to locking h is had to pass through, then does not add any condition control；
B single entry multiple exit：A certain paths after locking the acquisition of h are contained with the acquisition to locking w, but to lock w's
Obtain it is inevitable first obtain lock h, then do not contain on the path to locking w, added to locking w in other after the acquisition of lock h
Release operation；
C multiple entries single outlet：Acquisition operation to lock h necessarily causes to operate the acquisition for locking w, but to locking the acquisition of w
Then after lock w is performed and obtained in advance, a condition can be set to become by being reached without the path for obtaining operation to lock h
Measure vwFor true, both the conditional-variable and current thread ID, lock w determine, and recover previous section pair in the step
The deletion of original lock w operations, and cause the operation only just to measure v in conditionwValue carry out when being false, finally original
Variable v is changed before discharging the operation of wwValue be false；
D multiple entry/multiple exits：Acquisition to locking w is contained to a certain paths after locking the acquisition of h, but to locking w
Obtain can by without to lock h obtain operation path reach, then in C adding conditional control on the basis of, to every
A acquisition containing to lock h but the operation for not containing addition release w on the path obtained to lock w, and release operation is
In C conditional variables vwIt is worth to be performed during true；
E contains loop structure：Lock h is located in for, while loop structure with the acquisition to locking w, then original
There is the outside that the release operation to lock w is moved to the loop structure.
In the step (5), the context-aware conditions control added passes through vhwThe acquisition of the lock of control and release
Put, be under the protection of the lock w obtained in advance, i.e., it is all to vhwOperation be lock w obtain after and release advance
Capable, it can be drawn by 5 fundamental types of A, B, C, D, E.
In the step (3), the reparation for deadlock, is directly changed on source code, the source as program deadlock reparation
Code patch；Or directly repaired as patch in the bitcode files of LLVM or the bytecode files of Java.
The present invention compared with prior art the advantages of be：Reparation for program deadlock just has the success rate of higher, at the same time
Both new synchrolock will not be introduced, new deadlock will not be introduced, and larger performance will not be caused to reduce problem.
Brief description of the drawings
Fig. 1 realizes flow chart for the present invention's；Two of which set Lp (t) and WNk(t) represent respectively：Thread t its two
Between secondary lock operation the set for obtaining the set of operation and other locks being waited and notified is locked to other；
Fig. 2 is the realization for obtaining operation acq (h＆w) in advance for locking；
Fig. 3 is the reparation for obtaining operation acq () in synchronization module containing other locks；(a) in Fig. 3 is source program, Fig. 3
In (b) be repair after program；Wherein t1And t2Represent to lock one for two thread Thread, acq (X) and rel (Y)
The acquisition operation of X and the release to a lock Y operate, and h and w represent that related linear program is related to two locks of deadlock respectively,
P is in two other locks locked among h and w operations；Square frame containing strikethrough and arrow represent the acquisition in advance of lock,
W is just obtained in advance in the figure, itself and lock h is obtained together, i.e. acq (h＆w)；
Fig. 4 is the reparation for waiting wait () notice operations in synchronization module containing lock；(a) in Fig. 4 is source program, Fig. 4
In (b) be repair after program；Wait (k) represents that related linear program needs to wait the notice of another thread on lock k；It is right
In the situation of Fig. 4, in addition to the acquisition in advance for the lock w that the square frame containing strikethrough in figure and arrow represent, further relate to
The front and rear rel (w) and rel (k) carried out respectively of wait (k)；Acq (k＆w) is operated；
A kind of realization based on Pthreads for the code that Fig. 5 is controlled for context-aware conditions, with knot in the figure
Close the explanation of step of the present invention；
Fig. 6 is five kinds of basic control flow dispositions；
Fig. 7 is the illustration of five kinds of basic conditions in Fig. 6；
Fig. 8 is three programs containing deadlock；
Fig. 9 is recovery scenario of the present invention to three deadlocks in Fig. 8.
Embodiment
As shown in Figure 1, step of the present invention includes：For the per thread t in deadlock, the synchronization module of extraction procedure with
And the control flow in synchronization module, calculate in synchronization module to the set of other lock operations；According to obtained set, select
Most suitable candidate threads, directly perform and obtain lock operation in advance, and the control of additional context-aware conditions；According to
The control flow graph type of the synchronization module of extraction, does respective handling；The program after repairing is performed, if compiling failure,
Previous step is then returned to, selects other candidate threads, carries out deadlock reparation operation.If the candidate threads that can not select,
So the present invention can not repair the deadlock.
One thread obtains a lock, and the state for waiting another lock to be obtained is the necessary condition that deadlock occurs, thread
First lock obtained is known as the h of thread, waits lock to be obtained to be known as the w of thread.
Present invention specific implementation step is as follows：
(1) extract or require user's designated program synchronization module (acq (h) in i.e. each deadlock related linear program with
Part between acq (w), is denoted as site (h)~site (w)) and synchronization module in control flow.
(2) set operated in synchronization module site (h)~site (w) of the relevant each thread of deadlock to other locks is calculated,
Lp(t) set that acq (p) is operated in the synchronization module of thread t, WN are representedk(t) represent synchronization module in wait (k) and
The set of notify (k).
(3) the set L calculated according to step (2) each thread relevant to deadlockp(t) and WNk(t), choose
|Lp(t)+WNk(t) | minimum thread performs deadlock reparation operation, i.e., is replaced with acq (h＆w) as candidate threads
Acq (h) simultaneously deletes acq (w).
If ● | Lp(t)+WNk(t) |=0：Lock is performed to thread t and obtains operation in advance, deadlock reparation is carried out, that is, deletes
Acq (w) originally, and w and h are obtained into acq (h＆w) together.The operation acq of acquisition in advance (h＆w) of lock, uses
TryAcq (), the operation can immediately know that whether a lock obtains success, if as shown in Fig. 2, can not obtain two at the same time
A lock h and w, then release immediately the lock that (rel ()) has obtained, and avoids introducing new lock sequence.If thread cannot be at the same time
Obtain two locks, then the current lock obtained of thread release, circulation perform, until obtaining h and w locks at the same time.
If ● | Lp(t)+WNk(t)|≠0：Context-aware is added being performed to thread t on the basis of lock obtains in advance
Condition controls, and carries out deadlock reparation：
There are the operation of other acq (p) in synchronization module, as shown in figure 3, before p is obtained, release first carries
The w locks (i.e. rel (w) in figure) of preceding acquisition, then perform acq (p＆w) operations again.Utilize context-aware conditions
Control, adds a conditional-variable v before rel (w)hwAnd true is assigned a value of to it, it is assigned a value of after acq (p＆w)
False, while, it is necessary to another thread for needing to obtain w locks is being changed, that is, it is as follows to change its original acq (w)：
If the acq (w) runs succeeded, the conditional-variable v above set is first determined whetherhwWhether it is true, if true, then
Release lock w (i.e. rel (w)), and continues to obtain the lock, and if false, then instruction after continuing to execute is (i.e. from following
Jumped out in ring, break operations).Ensure that the thread that lock obtains in advance can obtain lock w with this, but it is related in deadlock
Another thread can not really take w lock.
There are wait (k) or notify (k) in synchronization module to operate, as shown in figure 4, with existing in synchronization module
Acq (p) operation repair mode it is similar, unlike perform wait (k) operation and or notify (k) operate when, it is necessary to
K locks are first discharged, then perform acq (k＆w) again, while be also required to set above-mentioned v in the same wayhwCondition and modification
Another obtains the thread of w.But there are a special circumstances herein, that is, it is same lock to lock k and lock h, at this time, only in advance
Obtain lock w, not just other settings.
" bool acq (Lock*h, Lock*w) " is the realization based on Pthreads of acq (h＆w) in Fig. 5, parameter therein
" h " and " w " is the lock h and lock w of selected thread respectively.In addition, three method " void in Fig. 5
setHWCondOn(Lock*hLock,Lock*wLock)”、“bool getHWCond(Lock*hLock,Lock*
WLock) " and " void setHWCondOff (Lock*hLock, Lock*wLock) " is to conditional-variable vhwThree behaviour
A kind of realization based on Pthreads made, corresponds to respectively：V is sethwFor true, v is readhwValue and set vhw
For false, parameter " hLock " therein and " wLock " are respectively the lock h of selected thread and lock w.
(4) five basic classes are listed according to the control flow graph type of the synchronization module extracted in step (1), Fig. 6
The processing mode of the specific controlling stream graph of type, Fig. 7 are this five kinds specific examples：
A ((a) in Fig. 7) single entry single exit：Lock w is directly obtained in advance, and deletes original acq (w)；
B ((b) in Fig. 7) single entry multiple exit：After acquisition in advance to locking w, in another branch (i.e. if (need_w)
Else branches) addition to lock w release rel (w)；
C ((c) in Fig. 7) multiple entries single outlet：After acquisition in advance to locking w, conditional-variable v is setwFor true,
And the adding conditional if (v on original acq (w)w)；
D ((d) in Fig. 7) multiple entry/multiple exit：After acquisition in advance to locking w, conditional-variable v is setwFor true,
Adding conditional if (the v on original acq (w)w), and add in another branch (i.e. the else branches of if (need_w)) of acq (h)
Add the release rel (w) to locking w；
E ((e) in Fig. 7) contains loop structure：After acquisition in advance to locking w, the rel (w) in circulation is moved to
Circulation outside.
Listed in Fig. 5 in the corresponding step to conditional-variable vwThree operation a kind of realizations based on Pthreads,
Including " void setPreAcqTaken (Lock*lock) ", " bool preAcqTaken (Lock*lock) ", " void
ClearPreAcq (Lock*lock) ", these three operations correspond to respectively：To vwIt is arranged to true, to vwValue reading,
V is setwThe lock w obtained in advance is should be for false, the parameter lock in these three realizations.
(5) according to the program performed after repairing, if compiling failure, returns to (3), selects other candidate threads,
Carry out deadlock reparation operation.If the candidate threads that can not select, then DFixer can not repair the deadlock；
As Fig. 8 sets forth three program P containing deadlock1,P2,P3, wherein deadlock is respectively D1, D2, D3,
Reparation of the invention in these three deadlocks is as shown in figure 9, specific repair process is as follows：
Such as (a) in Fig. 8, for program P1, thread t1With thread t2| Lp(t)+WNk(t) | value be 0, so line
Journey t1With thread t2All it is candidate threads, since the control flow of the synchronization module of two threads is all single-input single-output pattern,
One of thread can be randomly choosed and directly perform to obtain in advance and lock operation, so as to repair P1Deadlock D in program1。
The two repair modes are shown in (a) in Fig. 9 and (b) in Fig. 9.
Such as (b) in Fig. 8, for program P2, deadlock generation is in thread t1And t2Between, two threads
|Lp(t)+WNk(t) | value be 0, so thread t1With thread t2All it is candidate threads.If select thread t2Execution shifts to an earlier date
Lock operation is obtained, due to thread t2The control flow of the synchronization module of sum is singly to enter to have more, so will be without acq's (m)
Rel (m) operations are added at branch, that is, else branch outlets.(c) in Fig. 9 is the reparation of the deadlock.
Such as (c) in Fig. 8, for program P3, deadlock generation is in thread t1And t2Between, although thread t2Synchronization module
Between there are wait (n) to operate, still, since wait (n) is consistent with the object lock that acq (n) is operated, so and P1,P2
It is identical, thread t1With thread t2| Lp(t)+WNk(t) | value be 0, so thread t1With thread t2All it is candidate threads.
Since the control flow of the synchronization module of two threads is all single-input single-output pattern, it is straight that one of thread can be randomly choosed
Connect execution and obtain lock operation in advance.In (d) in Fig. 9, t have selected2Perform and obtain lock operation in advance.
The present invention on the premise of new deadlock is not introduced, has successfully repaired above three journey by obtaining lock operation in advance
Deadlock in sequence.
Validity check：
The characteristic information of 1 each benchmark of table
In order to verify the deadlock repairing effect effect of the present invention, using the data set of 9 benchmark to side of the invention
Method is tested, including DB Maintain, Bank Trans., Dining Philo., SQLite, OpenLDAP, and three
Different editions MySQL database, wherein first three benchmark only make a search use, remaining benchmark is equal
It is as shown in table 1 for the program being widely used in real world, the details of the data set.
Experimental situation：
Experiment carries out on a ThinkPad W540 workbench, it is furnished with Intel Core i7-4710MQ 2.5GHz
Processor, 16G memories, operating system Ubuntu14.04.
LLVM is used as platform, realizes method and GA and Grail in the invention.
Experimental procedure：
Table 2.GA, Grail, and DFixer repair comparing result
(1) deadlock of each program is repaired using the restorative procedure in GA, Grail and the present invention respectively, Ran Houyun
Program after three method reparations of row and each 100 times of the program do not repaired, the number that deadlock occurs before and after statistics is repaired.In order to
Deadlock odds is improved, in the specific location of program, is inserted into the random length of one's sleep.
(2) every kind of restorative procedure and the preprosthetic original program being directed in step 1, count the time of 100 operations (no
Add the Random-sleep time)；
(3) of the invention and other two kinds of restorative procedure implementation effects are contrasted.
Experimental result：
Table 2 have recorded reparation result of 3 kinds of recovery scenarios to 9 benchmark in detail.
In terms of performance influence, for the deadlock reparation in real world, on average, GA causes 15.8% performance
Decline, Grail causes 11.5% hydraulic performance decline, and the method for the present invention has resulted only in 2.1% hydraulic performance decline.
In terms of repairing effect, the present invention repairs result to 17 deadlocks in real world and counts again, and GA is successfully repaired
A deadlock of 7 (41%) therein, Grail have only successfully repaired a deadlock of 6 (35%) therein, and the side of the present invention
Method has successfully repaired a deadlock of 17 (100%).
In conclusion the self-repairing method obtained in advance based on lock proposed in the present invention can be repaired more effectively extremely
Lock, and new deadlock will not be introduced, while can only cause the performance of very little to reduce.
Above example is provided just for the sake of the description purpose of the present invention, and is not intended to limit the scope of the present invention.This hair
Bright scope is defined by the following claims.The various equivalent substitutions that do not depart from spirit and principles of the present invention and make and repair
Change, should all cover within the scope of the present invention.
Claims (5)
1. a kind of deadlock self-repairing method obtained in advance based on lock, it is characterised in that comprise the following steps：
(1) a deadlock D in preset sequence P and P, for the per thread in deadlock D, uses depth-first
Search (DFS) searches for and automatically extracts the function call information of each thread in D when deadlock D occurs, which includes
Per thread is how to reach deadlock point in D；The function call information may also require that user specifies；Based on this information,
Calculate the control flow chart CFG in the synchronization module and synchronization module of per thread, wherein synchronization module in D and refer to D
This in per thread, is locked the object of operation by the relevant part obtained twice between lock operation of middle per thread deadlock twice
Lock takes following mark：First is denoted as h locks, and second is denoted as w locks；
(2) calculate synchronization module in other lock operation set, the operation include to lock acquisition operation, etc. it is to be operated
Wait and notice operation Notify；
(3) according to the set obtained in step (2), suitable candidate threads are selected to perform deadlock reparation from deadlock D
Operation：If be related in the thread of deadlock, there are a thread, it is relevant deadlock to obtain between lock operation not twice
In the presence of the operation to other locks, second lock w of the directly deadlock relevant operation to the thread performs lock and obtains behaviour in advance
Make, and the operation before deletion to second lock w, carry out deadlock reparation；
(4) if not having thread to be selected in step (3), other threads are chosen, it meets that lock obtains twice in the thread
Minimum thread is operated to other locks between extract operation, performs and acquisition operation in advance is locked described in step (3), it is in addition attached
Add context-aware conditions to control, according to the lock action type between lock h operations and lock w operations, there is following A and B
Two kinds of situations：
A：If wherein there is the acquisition operation to other locks, it is p to remember the lock, then before the acquisition to locking p, addition
Variable vhw, which determines that the value for setting the variable be true by locking w and h, discharges lock w afterwards, and change original
To be retrieved as operating to obtaining while lock p and w to p, variable v is set afterwardshwValue be false；
B：If wherein exist to other locks etc. to be operated or notice operate, remember that the lock is locked for k, then to locking k
Before acquisition, variable v is addedhw, the variable by lock w and h determine that the value for setting the variable is true, is discharged afterwards
Lock w, and originally to lock k etc. it is to be operated after addition to lock k release operate, and to lock k and lock w it is same
When obtain operation, variable v is set afterwardshwValue be false；
(5) after the operation of step (3) or (4), repair the program destroyed because of obtaining in advance for w of lock and patrol
Volume；
(6) program after being repaired in step (3) or step (4) is denoted as P'；
(7) in addition the program P' after execution is repaired, if compiling failure, returns to (3), selects from deadlock D
Candidate threads, deadlock reparation is carried out according to the restorative procedure in step (3) and (4)；If the time that can not select
Route selection journey, then can not repair the deadlock.
2. the deadlock self-repairing method according to claim 1 obtained in advance based on lock, it is characterised in that：Institute
State in step (3), what second was locked is retrieved as in advance：Obtained together with first lock in the thread, based on lock
Exploratory acquisition operation tryAcq, can at once return a lock whether can be instantly captured, if two lock cannot be same
When obtain, then wherein obtained one lock is released immediately, and attempted next time, until two locks obtain at the same time；
Synchronous two locks of acquisition are realized using tryAcq, avoid introducing new lock order relation.
3. the deadlock self-repairing method according to claim 1 obtained in advance based on lock, it is characterised in that：Institute
State in step (5), repair the programmed logic destroyed because of obtaining in advance for w of lock：According to step (3) or (4)
The middle control stream of operation and step (1) extraction of the thread of middle selection before lock w is obtained in advance to two lock h and w
Relation, have following five kinds of basic conditions of A, B, C, D, E：
A single entry single exits：Acquisition operation to lock h necessarily causes to operate the acquisition for locking w, and obtains behaviour to lock w
The acquisition to locking h is had to pass through, then does not add any condition control；
B single entry multiple exit：A certain paths after locking the acquisition of h are contained with the acquisition to locking w, but to lock w's
Obtain it is inevitable first obtain lock h, then do not contain on the path to locking w, added to locking w in other after the acquisition of lock h
Release operation；
C multiple entries single outlet：Acquisition operation to lock h necessarily causes to operate the acquisition for locking w, but to locking the acquisition of w
Then after lock w is performed and obtained in advance, a condition can be set to become by being reached without the path for obtaining operation to lock h
Measure vwFor true, which is determined by both current thread ID, lock w, and recovers previous section pair in the step
The deletion of original lock w operations, and cause the operation only in conditional-variable vwValue carry out when being false, finally original
Variable v is changed before discharging the operation of wwValue be false；
D multiple entry/multiple exits：Acquisition to locking w is contained to a certain paths after locking the acquisition of h, but to locking w
Obtain can by without to lock h obtain operation path reach, then in C adding conditional control on the basis of, to every
A acquisition containing to lock h but the operation for not containing addition release w on the path obtained to lock w, and release operation is
In C conditional variables vwIt is worth to be performed during true；
E contains loop structure：Lock h is located in for, while loop structure with the acquisition to locking w, then original
There is the outside that the release operation to lock w is moved to the loop structure.
4. the deadlock self-repairing method according to claim 3 obtained in advance based on lock, it is characterised in that：Institute
State in step (4), the context-aware conditions control added passes through vhwThe acquisition and release of the lock of control, are
It is under the protection of the lock w obtained in advance, i.e., all to vhwOperation be lock w obtain after and release before carry out,
It can be drawn by 5 fundamental types of A, B, C, D, E.
5. the deadlock self-repairing method according to claim 3 obtained in advance based on lock, it is characterised in that：The step
Suddenly in (3), the reparation for deadlock, is directly changed on source code, the source code patch as program deadlock reparation；
Or directly repaired as patch in the bitcode files of LLVM or the bytecode files of Java.
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| CN102073588A (en) * | 2010-12-28 | 2011-05-25 | 北京邮电大学 | Code static analysis based multithread deadlock detection method and system |
| CN104978272A (en) * | 2015-07-08 | 2015-10-14 | 中国科学院软件研究所 | Program scheduling method for data race detection |
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| CN102073588A (en) * | 2010-12-28 | 2011-05-25 | 北京邮电大学 | Code static analysis based multithread deadlock detection method and system |
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Correction item: Claims Correct: Zheng Que False: Cuo Wu Number: 06-02 Page: Quan Wen Volume: 34 |