JP2010009296A - Software operation monitoring device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely monitor a task execution state in software operation monitoring, swiftly investigate the cause of abnormalities, and prevent MPU performance deterioration during actual operation. <P>SOLUTION: In a software operation monitoring device, an ID register 21 stores identification information (ID) given to an activated task. The ID includes information for specifying a task executed before execution of its own task. A control unit 23 monitors with hardware whether the task activation sequence is normal, based on the ID of the task activated this time and the ID of the preceding task activated previously. A log register group 22 stores information on the monitoring result, as log information, together with the ID in chronological order. When an abnormality occurs in a software execution state and timeout of a watchdog timer 24 is detected by a timer monitoring unit 25, the log information is saved from the log register group 22 to a recording unit 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a software operation monitoring device and a software operation monitoring method.

  2. Description of the Related Art Conventionally, there are the following information processing apparatuses regarding debugging techniques when executing a computer program having a multitask configuration. The information processing apparatus stores task identification information for identifying a task and stop target task identification information for identifying at least one stop target task to be stopped when the task is in a predetermined state in association with each other. A task state management unit that detects that the task has entered the predetermined state, and a task that has reached the predetermined state when the predetermined state detection unit detects that the predetermined state has been reached. And a stop task for stopping the stop target task stored in association with each other (see, for example, Patent Document 1).

JP 2006-127166 A

  However, in the technique disclosed in Patent Document 1, since the task execution state is monitored by another task being executed, the task cannot be normally monitored if the execution of the software runs out of control. There is. If the task cannot be monitored normally, there is a problem that the stop task cannot be started and the execution of the entire software cannot be stopped. Also, if an abnormality occurs during actual operation, information necessary for investigating the cause of the occurrence, such as task information, cannot be acquired, so the cause investigation work cannot be started immediately after the abnormality has occurred. There is a problem. Also, during actual operation, the execution speed of software in a microprocessor (MPU: Micro Processing Unit) may be slow, and performance may be significantly reduced. In addition, there is a problem that a great amount of man-hours are required for debugging a stop task.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a software operation monitoring apparatus and a software operation monitoring method capable of reliably monitoring the task execution state in order to solve the above-described problems caused by the prior art. It is another object of the present invention to provide a software operation monitoring apparatus and a software operation monitoring method capable of quickly investigating the cause of occurrence of an abnormality. It is another object of the present invention to provide a software operation monitoring apparatus and a software operation monitoring method that can prevent the performance of a microprocessor from being deteriorated during actual operation.

  In order to solve the above-described problems and achieve the object, this software operation monitoring apparatus and software operation monitoring method includes a plurality of tasks constituting the software, information for identifying the own task, and a task executed before the own task. Each time a task is started during software execution, task activation is performed based on the task identification information and the task identification information that was activated before that task. It is a requirement to monitor whether the order is normal. This monitoring result may be stored as log information together with task identification information. Further, when an abnormality is detected in the execution state of the software, log information may be recorded on a medium that can hold information even after the power is turned off, such as a nonvolatile memory.

  According to the software operation monitoring apparatus and the software operation monitoring method, the execution state of the software is monitored by hardware. Therefore, even when the execution of the software runs out of control, the operation of the task can be monitored. In addition, when an abnormality occurs during actual operation, the cause investigation work of the abnormality can be started immediately by acquiring log information. Further, since the microprocessor is not involved in monitoring task operations during actual operation, the load on the microprocessor is reduced.

  According to the software operation monitoring apparatus and the software operation monitoring method, the task execution state can be reliably monitored. In addition, there is an effect that the cause of the abnormality can be investigated quickly. In addition, there is an effect that it is possible to prevent the performance of the microprocessor from being lowered during actual operation.

  Exemplary embodiments of a software operation monitoring apparatus and a software operation monitoring method will be described below in detail with reference to the accompanying drawings.

(General description of the software operation monitoring device)
FIG. 1 is a block diagram illustrating an outline of a software operation monitoring apparatus according to an embodiment. As shown in FIG. 1, a software operation monitoring device (hereinafter referred to as a monitoring device) 10 includes an ID monitoring unit 11 and a recording unit 12. The ID monitoring unit 11 includes an ID register 21, a log register group 22, a control unit 23, a watchdog timer 24, and a timer monitoring unit 25. Identification information (hereinafter referred to as ID (Identifier)) is assigned in advance to each of a plurality of tasks constituting the software. This ID includes information for identifying the own task (hereinafter referred to as self-information) and information for specifying a task executed immediately before the self-task (hereinafter referred to as immediately preceding information).

  Each time a task is activated during execution of software, the ID assigned to the task is stored in the ID register 21. The control unit 23 monitors whether the task activation order is normal based on the ID of the task activated this time and the ID of the previous task activated before that. The monitoring result is stored in the log register group 22 in time series as log information together with the ID. When an abnormality occurs in the execution state of the software and the timer monitoring unit 25 detects a timeout of the watchdog timer 24, the log information is saved from the log register group 22 to the recording unit 12.

(Description of detailed configuration of software operation monitoring device)
FIG. 2 is a block diagram showing the configuration of the software operation monitoring apparatus. As shown in FIG. 2, the ID monitoring unit 11 includes an address decoding unit 26, a frequency divider 27, an AND gate 28, and a third interface unit 29 in addition to the functional blocks described above. The ID monitoring unit 11 is not particularly limited, and is configured by hardware such as an FPGA (Field Programmable Gate Array).

  The address decoding unit 26 decodes an address signal a1 provided from a microprocessor (MPU) 41 that executes software 42 to be monitored, and generates a select signal and an address signal that specify an access destination of the microprocessor 41. The frequency divider 27 divides the clock signal sent from the external clock source 43 to generate a count-up signal. The watchdog timer 24 is counted up by the count up signal. The AND gate 28 generates a clear signal when the ID of the task activated by the microprocessor 41 is written into the ID register 21. The watchdog timer 24 is set to an initial value by the clear signal. When the timer monitoring unit 25 detects a timeout of the watchdog timer 24, the timer monitoring unit 25 outputs a failure notification signal.

  The ID register 21 stores the ID sent from the microprocessor 41 each time the task is started by the microprocessor 41 and transfers it to the control unit 23. The control unit 23 includes a previous ID register 31, a latest ID register 32, a determination unit 33, a second interface unit 34, and a first interface unit 35. The latest ID register 32 stores the ID sent from the ID register 21. When an ID is sent from the ID register 21 to the latest ID register 32, the previous ID register 31 stores the ID stored in the latest ID register 32 until then.

  That is, the latest ID register 32 stores the ID of the latest task activated most recently (hereinafter referred to as the latest ID), and the previous ID register 31 stores the ID of the previous task activated one time before ( Hereinafter, ID is stored). However, the ID of the task activated for the first time is stored in the previous ID register 31. The determination unit 33 compares the immediately preceding information of the latest ID with the self information of the previous ID, and determines that the task activation order is normal (OK) if the previous information of the previous ID is included in the immediately preceding information of the latest ID. If it is not included, it is determined that the task activation order is abnormal (NG).

  The second interface unit 34 mediates when transferring log information from the monitoring device 10 to the detection device 44 connected to the monitoring device 10. The detection device 44 is a device that receives a failure notification signal from the timer monitoring unit 25 and detects that a failure has occurred in the execution of software in the microprocessor 41. The user operates the terminal 46 to remotely operate the detection device 44 via a network 45 such as a WAN (Wide Area Network) or a LAN (Local Area Network), and log information from the log register group 22 or the recording unit 12. Can be obtained.

  The first interface unit 35 mediates transfer of the latest ID stored in the latest ID register 32 and the information of the determination result of the determination unit 33 for the latest ID to the log register group 22 in association with each other. To do. Further, the first interface unit 35 transfers the log information read from the log register group 22 or the log information read from the recording unit 12 via the third interface unit 29 to the second interface unit 34. Mediate.

  The log register group 22 stores the latest ID and the information of the determination result of the activation order corresponding to the latest ID sent from the first interface unit 35 in time series. FIG. 3 is an explanatory diagram showing an example of the configuration of the log register group. As illustrated in FIG. 3, the log register group 22 includes a plurality of registers 51, 52, 53, and 54. In these registers 51, 52, 53, and 54, for example, data of an ID 56 and a flag (determination flag) 57 indicating the determination result of the corresponding activation order are stored, for example, in ascending order of addresses. When data is stored in all the registers of the log register group 22, the data is stored again from the register 51 having the smallest address in ascending order of address. If the determination result of the activation order is NG, time information (time stamp) at the time of NG determination, register information of the microprocessor 41 and peripheral devices, and the like may be stored together.

  The third interface unit 29 mediates when log information is transferred from the log register group 22 to the recording unit 12. The third interface unit 29 mediates when transferring log information from the recording unit 12 to the first interface unit 35. The third interface unit 29 mediates when log information is transferred from the recording unit 12 to the microprocessor 41. That is, the microprocessor 41 can read log information from the recording unit 12 via the third interface unit 29. The microprocessor 41 can also read log information from the log register group 22 by selecting the log register group 22.

  The recording unit 12 is composed of a nonvolatile memory, and records log information sent from the log register group 22 via the third interface unit 29. FIG. 4 is an explanatory diagram illustrating an example of information recorded in the recording unit. As shown in FIG. 4, the recording unit 12 includes, for example, device basic information 61 such as device type, device version number, and software version number, and ID determination OK information 62 including an ID and a corresponding determination flag (OK). In addition, information 63 at the time of ID determination NG including an ID and a determination flag (NG) corresponding to the ID is recorded. As in the illustrated example, time information (time stamp) at the time of NG determination, register information of the microprocessor 41 and peripheral devices, and other information useful for failure analysis are recorded together as information 63 at the time of ID determination NG. You may do it. The additional information at the time of NG determination contributes to speeding up when analyzing the failure factor.

(Description of ID assignment method)
FIG. 5 is an explanatory diagram showing an example of the task activation order. FIG. 6 is an explanatory diagram showing an example in which IDs are assigned based on the task activation order shown in FIG. As shown in these figures, the highest value in the ID is self-information and indicates the task number of the self-task (the number attached to the end of each task in FIG. 5). The lower value following the task number is the immediately preceding information, and indicates the task number of the task to be activated immediately before the own task. For example, when the ID is “1000”, “1” is a task number, and “000” indicates that there is no task activated immediately before. That is, task 1 with task number 1 is the first task. When the ID is “2159”, “2” is the task number, and “159” is the task number of the task to be activated immediately before. Therefore, task 2 is accessed from task 1, task 5 or task 9, but is not accessed from any other task.

(Description of ID determination method)
FIG. 7 is an explanatory diagram showing an example of log information for explaining the ID determination method. FIG. 7 shows log information stored in the log register group 22 when, for example, task 3, task 4, task 5, task 2, task 8, task 5,. Yes. In this example, since the ID of the address 0x04 is “4300”, the task to be activated immediately before the task 4 is only the task 3. Since the ID of address 0x00 is “3200”, the task activated immediately before task 4 is task 3. Accordingly, the activation order between the two tasks is normal, and the ID determination is OK. Therefore, the determination flag for task 4 is “0000”. On the other hand, since the ID of the address 0x14 is “5400”, the task to be activated immediately before the task 5 is only the task 4. However, since the ID of address 0x10 is “8270”, the task activated immediately before task 5 is task 8. Therefore, since the activation order between the two tasks is abnormal, the ID determination is NG, and the determination flag for task 5 is “8000”.

(Description of normal operation)
FIGS. 8 and 9 are a sequence diagram and a timing chart, respectively, for explaining the normal operation of the software operation monitoring apparatus according to the embodiment. First, signals related during normal operation will be described with reference to FIG. In FIG. 9, an address signal a 1, a data signal d 1, and a write control signal w 1 are given from the microprocessor 41 to the address decoding unit 26. The select signal s 3, the data signal d 2, and the write control signal w 2 are given from the address decoding unit 26 to the ID register 21. The data signal d3 is given from the ID register 21 to the previous ID register 31 or the latest ID register 32. The select signal s6, the address signal a6, the data signal d6, and the write control signal w6 are given from the first interface unit 35 to the log register group 22.

  As shown in FIGS. 8 and 9, when the first task is activated, the microprocessor 41 asserts the address (address signal a1) of the ID register 21 and the ID (data signal d1) of the first task, The write control signal w1 is asserted. The address decoding unit 26 determines that the write is to the ID register 21 and fetches the data (step S1). Then, the address decoding unit 26 asserts the select signal s3, the data signal d2, and the write control signal w2 to the ID register 21, and writes the ID of the first task in the ID register 21 (step S2).

  At this time, the select signal s3 input to the AND gate 28 and the write control signal w2 are both asserted, and the AND condition is satisfied, so the AND gate 28 asserts the clear signal. Thereby, the watchdog timer 24 returns to the initial value (step S3). Further, the ID register 21 transfers the ID of the first task to the control unit 23 by the data signal d3 (step S4). The control unit 23 determines that this is the first ID write, and writes this ID in the previous ID register 31 (step S5).

  When the second task is activated, the watchdog timer 24 returns to the initial value and the ID is transferred from the microprocessor 41 to the control unit 23 in the same manner as in the first time (steps S6 to S9). The control unit 23 writes the ID in the latest ID register 32 (step S10). Next, the determination unit 33 reads the previous ID and the latest ID from the previous ID register 31 and the latest ID register 32, respectively, and determines whether the task activation order is normal by the above-described ID determination method (step S11). . Then, the control unit 23 associates the latest ID stored in the latest ID register 32 with the information of the determination result by the determination unit 33, asserts it as the data signal d6, and selects the select signal s6 and the log register group 22 The head address (address signal a6) is asserted. Further, the control unit 23 asserts the write control signal w6, and writes the ID and the information of the determination result corresponding to the log register group 22 (step S12).

  Next, the control unit 23 moves the latest ID stored in the latest ID register 32 to the previous ID register 31 (step S13). Then, the control unit 23 automatically updates the address of the log register group 22 in preparation for the next writing of data to the log register group 22 (step S14). The activation of the third and subsequent tasks is the same as in the second case.

(Description of operation when a failure occurs)
FIGS. 10 and 11 are a sequence diagram and a timing chart, respectively, for explaining the operation of the software operation monitoring apparatus according to the embodiment when a failure occurs. First, signals related to the occurrence of a failure will be described with reference to FIG. In FIG. 11, when reading log information from the log register group 22, the select signal s 6, the address signal a 6, and the read control signal r 6 are given from the first interface unit 35 to the log register group 22. When transferring the read log information to the recording unit 12, the select signal s 7, the address signal a 6, and the write control signal w 6 are given from the first interface unit 35 to the third interface unit 29. At either timing, the data signal d6 is supplied from the log register group 22 to the third interface unit 29. The select signal s8, the address signal a8, the data signal d8, and the write control signal w8 are given from the third interface unit 29 to the recording unit 12.

  As shown in FIGS. 10 and 11, it is assumed that an abnormality occurs in the execution state of the software after the n-th task is activated. If the watchdog timer 24 does not return to the initial value due to the occurrence of this abnormality, the timer monitoring unit 25 detects a counter overflow (OVF) and asserts a failure notification signal to the control unit 23 (step S21). The control unit 23 asserts the head address (address signal a6), the select signal s6, and the read control signal r6 of the log register group 22, and reads the log information (data signal d6) from the log register group 22 (step S22).

  Subsequently, the control unit 23 negates the select signal s6 and the read control signal r6, then asserts the select signal s7 and the write control signal w6, and transfers the log information to the third interface unit 29 (step S23). The third interface unit 29 asserts the write control signal w8 after asserting the head address (address signal a8), the log information (data signal d8), and the select signal s8 of the recording unit 12, and sends the log information to the recording unit 12. Write (step S24). Thereafter, while automatically updating the addresses of the log register group 22 and the recording unit 12, the steps S22 to S24 are repeated to transfer all log information from the log register group 22 to the recording unit 12 for recording. In addition to triggering the assertion of the failure notification signal, the log information can be saved from the log register group 22 to the recording unit 12 by the user operating the terminal 46 or by an instruction from the microprocessor 41. it can.

(Description of remote reading operation of log information)
12 and 13 are a sequence diagram and a timing chart, respectively, for explaining the operation of reading log information from the software operation monitoring apparatus according to the embodiment. First, signals related to remote reading of log information from the recording unit 12 will be described with reference to FIG. In FIG. 13, the address signal a <b> 9 and the read control signal r <b> 9 are given from the detection device 44 to the second interface unit 34. The data signal d9 is given from the second interface unit 34 to the detection device 44. The address signal a10 and the read control signal r10 are given from the second interface unit 34 to the first interface unit 35. The data signal d10 is given from the first interface unit 35 to the second interface unit 34. The select signal s7, the address signal a6, and the read control signal r6 are given from the first interface unit 35 to the third interface unit 29. The data signal d6 is given from the third interface unit 29 to the first interface unit 35. The select signal s8, the address signal a8, and the read control signal r8 are given from the third interface unit 29 to the recording unit 12. The data signal d8 is given from the recording unit 12 to the third interface unit 29.

  As shown in FIGS. 12 and 13, when the user operates the terminal 46 and tries to read the log information from the recording unit 12, the detection device 44 recognizes the reading instruction from the terminal 46 (step S31). . Then, after detecting the head address (address signal a9) of the recording unit 12, the detection device 44 asserts the read control signal r9 and requests the second interface unit 34 to read the log information (step S32). The second interface unit 34 asserts the address signal a10 and the read control signal r10, and requests the first interface unit 35 to read the log information (step S33). The first interface unit 35 asserts the address signal a6, the select signal s7, and the read control signal r6, and requests the third interface unit 29 to read the log information (step S34). The third interface unit 29 asserts the address signal a8, the select signal s8, and the read control signal r8, and requests the recording unit 12 to read log information (step S35).

  Then, the third interface unit 29 reads log information (data signal d8) from the recording unit 12 (step S36). After confirming the output of the log information (data signal d8) from the recording unit 12, the third interface unit 29 negates the read control signal r8 and outputs the log information (data signal d6) to the first interface unit 35 (step) S37). The first interface unit 35 negates the read control signal r6 after confirming the output of the log information (data signal d6), and outputs the log information (data signal d10) to the second interface unit 34 (step S38). The second interface unit 34 negates the read control signal r10 after confirming the output of the log information (data signal d10), and outputs the log information (data signal d9) to the detection device 44 (step S39). After the output of the log information (data signal d9) is confirmed, the detection device 44 negates the read control signal r9 and temporarily accumulates the log information. Thereafter, the detecting device 44 repeats Steps S32 to S39 while automatically updating the address for reading the log information from the recording unit 12, reads all the log information from the recording unit 12, and batches the read log information. The result report is transferred to the terminal 46 (step S40).

  If the first interface unit 35 asserts the select signal s6 instead of the select signal s7 and selects the log register group 22 in step S34, the log information is read from the log register group 22 instead of the recording unit 12. be able to. Further, the microprocessor 41 selects the log register group 22 by the select signal s4 via the address decoding unit 26, and designates the start address of the log register group 22 by the address signal a4, so that the log information is read from the log register group 22. Can be read out. Further, the microprocessor 41 selects the third interface unit 29 by the select signal s5 through the address decoding unit 26, and designates the head address of the recording unit 12 by the address signal a4, whereby the log information is received from the recording unit 12. Can be read.

  In the above configuration, the ID monitoring unit 11 has a function as monitoring means. The recording unit 12 has a function as a recording unit. Further, the log register group 22 has a function as log storage means. The third interface unit 29 has a function as a log transfer unit from the monitoring unit to the recording unit.

  As described above, according to this embodiment, since the ID monitoring unit 11 is configured by hardware, the execution state of software can be monitored by hardware. Therefore, even when the execution of software runs out of control, the task operation can be monitored. Therefore, the task execution state can be reliably monitored. Further, when an abnormality occurs during actual operation, for example, when the user operates the terminal 46 to acquire log information, the cause investigation operation of the abnormality can be started immediately. Therefore, the cause of the abnormality can be investigated quickly. In addition, during actual operation, the microprocessor 41 is not involved in monitoring task operations, so the load on the microprocessor 41 is reduced. Therefore, it is possible to prevent the performance of the microprocessor 41 from being deteriorated during actual operation. Further, by saving the log information in the recording unit 12, it is possible to avoid the log information from disappearing when the power is turned off or reset. In addition, by recording log information, when an abnormality occurs in the execution state of the software and the watchdog timer 24 times out, or when a failure due to other causes occurs, the task that causes it can be easily performed. Can be specified. These effects are effective not only during actual operation but also during software debugging. Further, even during actual operation, the user can recognize and deal with minor problems that do not lead to a failure by operating the terminal 46 and acquiring log information. Contributes to the improvement of sex.

  The following additional notes are disclosed with respect to the embodiment described above.

(Supplementary note 1) A software operation monitoring device for monitoring the operation of software composed of a plurality of tasks to which identification information including information for identifying a task and information for identifying a task to be executed before the task is attached There,
And a monitoring means for monitoring a task activation order based on the identification information attached to the task activated this time and the identification information attached to the previous task activated before that. Software operation monitoring device.

(Additional remark 2) The software operation | movement monitoring apparatus of Additional remark 1 characterized by further comprising the log memory | storage means to memorize | store the said identification information of the started task as log information in order of starting.

(Supplementary note 3) The software operation monitoring apparatus according to supplementary note 2, wherein the log information includes information on a monitoring result of a task activation order by the monitoring unit in association with the identification information.

(Additional remark 4) It is further provided with the non-volatile recording means which records the said log information, and the means to transfer the said log information from the said monitoring means to the said recording means, when abnormality is detected in the execution state of the said software 4. The software operation monitoring apparatus according to appendix 2 or 3, characterized by:

(Additional remark 5) It further has an interface which mediates when transferring the log information from the monitoring means to the other apparatus between the other apparatus connected to the network and the monitoring means. The software operation | movement monitoring apparatus as described in any one of -4.

(Supplementary Note 6) The software operation monitoring according to any one of Supplementary notes 2 to 5, wherein the monitoring unit further includes a unit that transfers the log information to a processing device that executes the software. apparatus.

(Supplementary note 7) When executing software composed of a plurality of tasks to which identification information including information for identifying the task and information for identifying the task to be executed before the task is executed, the task activated this time A software operation monitoring method, comprising: monitoring a task activation order based on the identification information attached and the identification information attached to a previous task activated before the identification information.

It is a block diagram which shows the outline of the software operation | movement monitoring apparatus concerning embodiment. It is a block diagram which shows the structure of the software operation | movement monitoring apparatus concerning embodiment. It is explanatory drawing which shows an example of a structure of a log register group. It is explanatory drawing which shows an example of the information recorded on a recording part. It is explanatory drawing which shows an example of the starting order of a task. It is explanatory drawing which shows the example of provision of ID. It is explanatory drawing which shows an example of the log information for demonstrating an ID determination method. It is a sequence diagram explaining the operation | movement at the time of normal of the software operation | movement monitoring apparatus concerning embodiment. It is a timing chart explaining operation at the time of normal of a software operation monitoring device concerning an embodiment. It is a sequence diagram explaining the operation | movement at the time of the failure generation of the software operation | movement monitoring apparatus concerning Embodiment. It is a timing chart explaining the operation | movement at the time of the failure generation of the software operation | movement monitoring apparatus concerning Embodiment. It is a sequence diagram explaining the operation | movement which reads log information from the software operation | movement monitoring apparatus concerning embodiment. It is a timing chart explaining the operation | movement which reads log information from the software operation | movement monitoring apparatus concerning embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Software operation monitoring apparatus 11 Monitoring means 12 Recording means 22 Log storage means 29 Log transfer means from monitoring means to recording means

Claims (5)

A software operation monitoring device that monitors the operation of software composed of a plurality of tasks with identification information including information identifying the invoking task and information for identifying a task executed before the invoking task,
Monitoring means for monitoring the task activation order based on the identification information attached to the task activated this time and the identification information attached to the previous task activated previously;
A software operation monitoring apparatus comprising: Log storage means for storing the identification information of the activated task as log information in the order of activation;
The software operation monitoring apparatus according to claim 1, further comprising:   The software operation monitoring apparatus according to claim 2, wherein the log information includes information on a monitoring result of a task activation order by the monitoring unit in association with the identification information. Non-volatile recording means for recording the log information;
Means for transferring the log information from the monitoring means to the recording means when an abnormality is detected in the execution state of the software;
The software operation monitoring apparatus according to claim 2, further comprising:   Attached to the task that was started this time when executing software that consists of multiple tasks with identification information that includes information that identifies the task and information that identifies the task to be executed before the task A software operation monitoring method, comprising: monitoring a task activation order based on the identification information and the identification information attached to a previous task activated before the identification information.

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