ENHANCING WEAK CONSISTENCY

• US 20160103752A1
• Filed: 12/11/2014
• Published: 04/14/2016
• Est. Priority Date: 10/09/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: BATES, Cary L., KING, Justin K., HELGESON, Lee, SCHLICHT, Michelle A.
• Granted Patent: US 9,594,667 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/362 Software debugging
• CPC Class Codes: G06F 11/3632 of specific synchronisation aspects

Abstract

Methods to discover weak consistency errors in an application, by executing, by a debugger, a first thread of the application, by, determining that a first instruction in the first thread specifies to store a first value at a first memory address, setting a current value stored in the first memory address as an old value for the first memory address in a container for the first thread, executing the first instruction to store the first value at the first memory address, and setting the first value as a new value for the first memory address in the container for the first thread. The debugger then executes a second thread of the application, by restoring old values in the containers for all other threads and restoring a new value for each memory address specified in a container for the second thread to its respective memory address.

Claims

1. A method to discover errors in an application executed on a computing system, comprising:

executing, by a debugger, a first thread of the application, comprising;

upon determining that a first instruction in the first thread specifies to store a first value at a first memory address;

setting a current value stored in the first memory address as an old value for the first memory address in a container for the first thread;

executing the first instruction to store the first value at the first memory address; and

setting the first value as a new value for the first memory address in the container for the first thread;

executing, by the debugger, a second thread of the application, comprising;

restoring the old value in the container for the first thread to the first memory address; and

restoring a new value for each memory address specified in a container for the second thread to a respective memory address.

2. The method of claim 1, further comprising:

upon determining that the container for the first thread does not include a record for the variable, creating a record for the variable in the container for the first thread.

3. The method of claim 1, further comprising:

upon determining that the first instruction is a sync instruction, clearing the values in the container for the first thread.

4. The method of claim 1, wherein the second thread is executed by the debugger upon determining at least one of:

(i) that the debugger has executed a predefined number of instructions of the first thread, (ii) that a second instruction of the first thread is a blocking type of instruction, and (iii) that an amount of time the debugger has executed the first thread exceeds a predefined time threshold.

5. The method of claim 1, wherein executing the second thread further comprises:

restoring, for each thread of the application, each old value in a respective container of each thread to a respective memory address associated with each old value prior to restoring the new value for each memory address in a container for the second thread.

6. The method of claim 1, wherein executing the second thread further comprises:

upon determining that a second instruction in the second thread specifies to store a second value at a second memory address;

setting a current value stored in the second memory address as an old value for the second memory address in the container for the second thread;

executing the second instruction to store the value at the second memory address; and

setting the value as a new value for the second memory address in the container for the second thread.

7. The method of claim 1, further comprising:

upon determining that executing a second instruction in the second thread causes a weak consistency error, returning an indication of the weak consistency error.