JP2009054016A - Image forming apparatus, image forming method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus capable of preventing the generation of garbage collection (GC) as much as possible during the execution of a job in an image forming apparatus having a GC function. <P>SOLUTION: The image forming apparatus is provided with: an execution means for executing a job by the execution of a program allocated to a memory area and outputting a GC request at previously specified timing; and a GC generation means for generating GC in response to the reception of a GC request. The timing is any one of at the execution time of switching processing to image display concerned with a program selected by a user by a UI device after selecting the program by the user, at the end of program execution, at the execution of processing by a hardware device in an idle state in which the program is not driven, and at the shift of the UI device to a power saving mode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that suppresses performance degradation due to occurrence of garbage collection (GC), a method for suppressing performance degradation due to occurrence of GC, and a program for realizing the method.

  The operating system (OS) is used as software to manage the entire system by providing basic functions commonly used by various application software, such as input / output functions such as keyboard input and screen output, and memory management. ing. As one of the OS memory management functions, a garbage collection (GC) function is known in which a memory area that is no longer used by a program or a memory area that is interposed between programs is collected to increase a continuously available memory area. ing.

  In the execution environment of the Java (registered trademark) language, that is, the Java (registered trademark) virtual machine (JVM), the JVM itself has a GC function, so that even if the programmer does not need to delete the unnecessary object, The GC function automatically collects an object when it is no longer needed, and releases the memory area to make it reusable. For this reason, it is possible to effectively prevent the occurrence of erroneous release of the memory area, memory leak (release leak), and the like.

  On the other hand, in a personal computer (PC) or server device having a GC function, an object is erased collectively at an arbitrary timing and a memory area is collected, so that the CPU is occupied during the period during which the GC function is operating. There is a problem that the job processing being executed is interrupted.

  Therefore, there has been proposed a technique for shortening the interruption time of the entire apparatus while effectively preventing the occurrence of a memory leak or the like due to the GC function (see Patent Documents 1 to 5).

  In the technique described in Patent Document 1, when a storage block for storing data is newly reserved, it is determined whether the data has relatively short lifetime or relatively long data, and is stored thereby Processing required for GC by dividing an area, increasing GC execution frequency for a memory area storing data with a relatively short lifetime, and reducing GC execution frequency for a memory area storing data with a relatively long lifetime The overall time is reduced.

  In the technique described in Patent Document 2, the GC process is executed in the thread while the process of the thread is interrupted according to the real time set in the thread being executed. The minimum necessary GC is executed to ensure that the heap area is not depleted.

  In the technique described in Patent Literature 3, a memory usage situation simulation is executed based on memory usage situation data and heap parameters to optimize the memory usage situation.

  In the technique described in Patent Document 4, a memory is divided into a new generation and an old generation, an object is assigned to the new generation, a period for storing the new generation is determined according to the class of the object, and the new generation is based on the period. The system is moved from the previous generation to the previous generation, and the processing time of the recovery process of the storage area for storing unnecessary data during the startup and execution of the program is shortened and performed efficiently.

In the technique described in Patent Document 5, a temporary object that is temporarily and repeatedly generated for each request is reused to limit the communication pattern, thereby suppressing the occurrence of GC.
JP 2002-278828 A JP 2004-234546 A JP 2004-5486 A JP 2006-171927 A JP 2007-86838 A

  The above-described GC function is not limited to a PC or server device, but is also adopted in a multi-function peripheral equipped with a plurality of functions such as a copy function, a scanner function, and a printer function. In a multi-function peripheral, first copy time, continuous copying speed, etc. are required as catalog specifications. Here, the first copy time is the time required to copy only one original, and the continuous copying speed is the number of copies that can copy one original per minute.

  As shown in FIG. 1, an image forming apparatus such as a multifunction peripheral receives software 10 for causing a CPU to execute processing and an input from a user, sends it to the software 10, receives an update from the software 10, and draws an image. Receiving a request from the software 10, an engine device 12 such as a printer or a scanner that executes processing upon receiving a request from the software 10, and accepting parameter settings from the software 10, A / D conversion processing, scaling processing, dithering And an IPU device 13 that executes image processing such as processing.

  In FIG. 1, the job is started when the software 10 receives an input received by the UI device 11 as an event (keyInput). The software 10 sends a request to the engine device 12, and the engine device 12 executes processing (t1). The software 10 sends parameters to the IPU device 13 to execute image processing based on the set parameters (t2). The software 10 sends a display update instruction to the UI device 11, and the UI device 11 draws an image based on the instruction (t3). The software 10 sends a request to the engine device 12, and the engine device 12 executes the process (t4), but a GC occurs and the job is interrupted (t5). After the GC is finished, the software 10 sends the request to the engine device 12 again, and the engine device 12 executes the process again (t6). The software 10 sends a display update instruction to the UI device 11, and the UI device 11 draws an image (t6), and the job ends.

  In general, the catalog specification does not consider the interruption time t5 of the execution job by GC, and the value obtained by adding t1 to t4 and t6 is described as the processing time. For this reason, if a job being executed is interrupted due to the occurrence of GC, the catalog specification cannot be satisfied. In the apparatus having the GC function, since the GC can occur in any situation, it is not possible to avoid the job interruption 100%. Therefore, in order to satisfy the catalog specification, it is necessary to prevent the occurrence of GC as much as possible during job execution.

  Therefore, it is desired to provide an apparatus and a method that can suppress performance degradation by preventing the occurrence of GC as much as possible during job execution in an image forming apparatus having a GC function.

  In order to solve the above-described problem, the present invention provides an image forming apparatus including a Java (registered trademark) VM and including a platform having a GC function. It is assumed that there is a considerable interval, and a function is provided for outputting a GC request at a predetermined timing and forcibly generating a GC in response to reception of the GC request. Since GC does not occur for a while after the end of the GC, by executing the job during this time, it is possible to suppress the performance degradation at the time of job execution.

  That is, according to the present invention, an image forming apparatus having a garbage collection (GC) function for collecting and reusing a memory area that is no longer needed among memory areas to which a program is allocated, It is possible to provide an apparatus that includes a job execution unit that executes a job and outputs a GC request at a timing specified in advance, and a GC generation unit that generates a GC in response to reception of the GC request.

  As the above timing, in order to suppress the performance degradation at the time of job execution, at the time of switching the image display by the display device provided in the image forming apparatus, at the end of the job, in the idle state where the job execution means is not operating, It can be either when processing is performed by a hardware device provided in the image forming apparatus or when the display device is shifted to a power saving mode. The display device corresponds to the UI device 11 in FIG. 1, and the hardware device corresponds to the engine device 12 and the IPU device 13. The job execution means executes a job by executing a program and outputs a GC request at a timing specified in advance, thereby outputting a GC request at the end of the job or in an idle state. , GC can be generated.

  The GC generating means can check the remaining memory amount (memory size) and generate a GC when the remaining memory amount is equal to or less than a preset threshold value. If there is a sufficient amount of remaining memory, the possibility of occurrence of GC is low, but if the amount of remaining memory decreases, the possibility of occurrence of GC increases. Once this GC occurs, no GC occurs for a while after that. For this reason, by forcibly generating GC when the remaining memory amount is equal to or less than the threshold, the job is executed while no GC is generated, thereby suppressing performance degradation.

  In addition, the GC generation unit can hold the previous GC end time, and can generate a GC when the time from the GC end time to the reception of the GC request is equal to or greater than a threshold value. As described above, GC can occur in any situation. In addition, the longer the elapsed time from the previous GC end time, the higher the possibility of occurrence of GC. For this reason, when the elapsed time is equal to or greater than the threshold value, the GC can be forcibly generated, and the job can be executed while no subsequent GC is generated.

  In the above description, the time from the end of the previous GC to the reception of the GC request is used. However, the number of execution jobs can be counted, and a GC can be generated when the number of execution jobs exceeds a threshold value.

  In the present invention, in addition to the image forming apparatus, a method for suppressing performance degradation due to occurrence of GC can also be provided. The method includes outputting a GC request at a predesignated timing and generating a GC in response to receiving the GC request.

  The present invention can also provide an image forming apparatus-readable GC generation program for realizing the above method.

  The present invention is based on the premise that there is a considerable time interval between the occurrence of a GC and the occurrence of the next GC. That is, once a GC occurs, the GC does not occur for a while. is there. In one embodiment of the image forming apparatus of the present invention, the image forming apparatus includes a GC generator that forcibly generates GC in addition to the software 10, the UI device 11, the engine device 12, and the IPU device 13 shown in FIG. Prepare. In the present embodiment, the image forming apparatus includes a platform having a GC function, including a Java (registered trademark) VM.

  The software 10 receives an input from the user, sends a request to the engine device 12, and causes the engine device 12 to execute processing. Further, the software 10 sends a parameter to the IPU device 13, causes the IPU device 13 to set, and executes image processing using the set parameter. Further, the software 10 receives an input from the UI device 11 and gives an instruction for updating the display image to the UI device 11. For example, when an application is selected and processing is performed by the selected application, the UI device 11 performs image drawing to update the image display, the IPU device 13 executes image conversion processing, and the engine device 12 performs printing processing. Etc. These processes are a series of processes, that is, one job, and the software 10 executes a job that is such a series of processes.

  The software 10 is executed by a CPU that controls the entire image forming apparatus and performs the above processing. Therefore, although the software 10 itself does not actually execute processing, in order to facilitate the description, the following description will be made assuming that the software 10 performs processing.

  The UI device 11 is an operation unit, and includes a CPU and a memory for receiving input from a user and performing image drawing. The engine device 12 includes hardware such as a scanner, a printer, a fax machine, and a copier. The IPU device 13 includes a CPU, an ASIC, a ROM, a RAM, and the like in order to execute image processing.

  With reference to FIG. 2, the software 10 and the GC generator 14 used in the image forming apparatus of this embodiment will be described. In addition to the processing described above, the software 10 is configured to output a GC request to the GC generator 14 at a predetermined timing. The GC generator 14 is configured to generate a GC in response to a GC request from the software 10.

  In FIG. 2, the software 10 generates an event (ev) in the software 10, calls the GC request gcReq () by this event, and outputs gcReq () to the GC generator 14. The GC generator 14 receives gcReq (), calls gc () by gcReq (), and generates GC by gc (). gcReq () and gc () are operations, that is, methods, for objects that each object has in object-oriented programming.

  In order to generate a GC at a time when it is desired to generate a GC, the software 10 outputs a GC request to the GC generator 14 at a timing specified in advance. The GC generator 14 receives a GC request and forcibly generates a GC. As a result, for example, by executing a job immediately after the GC is finished, it is possible to avoid the occurrence of GC during the execution of the job, and it is possible to suppress performance degradation during job execution. Here, the timing can be the following timing.

  One is when the UI device 11 performs a process of switching to image display related to the application when the user selects an application (copy / printer / fax / scanner / document box). The application is selected when the user presses an application switching key, and the image display is switched when the UI device 11 switches to an image display related to the application selected by the user in response to pressing of the key. Done.

  The process in this case will be described in detail with reference to FIG. 3. The job is started when the software device 10 receives an input received from the user by the UI device 11 as an event (keyInput). The software 10 executes a job for sending update (), which is a display update instruction, to the UI device 11. The UI device 11 receives update () and displays a new image by drawing an image related to the application selected by the user.

  This image drawing is a process performed by the CPU included in the UI device 11 and is different from the CPU that executes the GC. Therefore, the image drawing is not affected by the occurrence of the GC. Also, there is a sufficient time interval from the start of the image display switching process to the next input by the user in terms of the human operating speed. For this reason, by forcibly generating GC at the time of executing this switching process, it is possible to suppress the occurrence of GC for a while after switching. Although execution of GC and processing by the UI device 11 are performed in parallel, as shown in FIG. 3, when the execution period of GC is long, an input disable period T to the UI device 11 occurs. However, the period T is a short period, and even if input cannot be performed during that period, it is within a sufficiently allowable range.

  The second is when the job executed on the application program ends. When jobs are continuously executed on the same application, for example, when another user takes a copy after making a copy, the application switching as described above does not occur. For this reason, the method of generating GC during image drawing by the UI device cannot be adopted.

  Referring to FIG. 4 in detail, the software 10 sends exec () to the IPU device 13 to execute processing, and sends exec () to the engine device 12 to execute processing. The engine device 12 returns a response (event) to the software 10, and the software 10 sends update () for updating the display to the UI device 11. Further, the engine device 12 returns a response (event) indicating that the processing has been completed, and the software 10 sends update () to the UI device 11. By sending this update (), the software 10 ends the job. While there is not enough time to execute GC during job execution, there is sufficient time from the transmission of this update () to the next input by the user as shown in FIG. Thus, when the job is completed, the software 10 outputs a GC request, and the GC generator 14 forcibly generates GC, so that the occurrence of GC can be suppressed for a while after the job ends.

  During the execution of the GC, the processing by the UI device 11 is performed in parallel. However, as shown in FIG. 4, when the execution period of the GC is long, an input disable period T to the UI device 11 occurs. However, the period T is a short period, and even if input cannot be performed during that period, it is within a sufficiently allowable range.

  The third time is when the hardware device included in the image forming apparatus, that is, the UI device 11, the engine device 12, and the IPU device 13 are running and in an idle state in which the application program is not operating. When described in detail with reference to FIG. 5, the software 10 sends exec () to the engine device 12 and the IPU device 13 to execute processing. The engine device 12 returns a response (event) to the software 10 after the processing is completed. In response to the response, the software 10 sends update () to the UI device 11. In the sequence shown in FIG. 5, the process by the engine device 12 takes time, and there is sufficient time from the start of execution of the process to returning a response to the software 10. During this time, the software 10 is not operating and is in an idle state.

  For this reason, a point where the influence of the GC is acceptable or a point where there is no influence in the hardware processing, that is, while the engine device 12 is executing the process, the GC is forcibly generated until the next GC occurs. By opening the interval, it is possible to achieve the catalog specifications such as the first copy time and the continuous copy speed by preventing the occurrence of GC during job execution.

  The fourth time is when the UI device 11 shifts to the power saving mode. There are various power saving modes. Here, only the UI device 11 is turned off, and the power saving state is a state in which only the UI device 11 is turned off. Since this power saving state is a state where there is virtually no user input, there is little influence by forcibly generating GC here.

  Referring to FIG. 6 in detail, the software 10 generates an event “changeMode ()”, calls off (), and sends it to the UI device 11 in order to shift to the power saving mode. The UI device 11 receives off () and turns off the power of the UI device 11. When the power of the UI device 11 is turned off, there is no input from the user, so there is sufficient time for the GC to function. For this reason, GC can be generated when shifting to the power saving mode. As a result, the occurrence of GC during the subsequent job execution can be suppressed for a while. Note that if the process is being executed via the network even if the UI device 11 is OFF, a job by the software 10 is being executed. Therefore, no GC is generated at this timing. For example, a GC is generated at the end of the job. There is a need.

  Next, an embodiment of the GC generator 14 will be described with reference to the drawings. As a first embodiment of the GC generator 14, there is one that generates a GC in response to a GC request as shown in FIG. The GC generator 14 has only a function of generating a GC in response to a GC request.

  As a second embodiment of the GC generator 14, the remaining memory amount in the heap area at the time of receiving the GC request is checked, and it is confirmed whether or not the remaining memory amount is less than or equal to the threshold value. Only those that generate GC. The heap area is a memory area that can be secured freely regardless of the application. The threshold value may be a fixed value given as an initial value of the image forming apparatus, or may be a value that can be changed by the user while the image forming apparatus is operating. However, when the software 10 is changed during operation, the software 10 issues a GC request to the GC generator 14 immediately after that. This is because it is checked whether the remaining memory amount is equal to or less than the changed threshold value, and if it is equal to or less than the threshold value, GC must be generated.

  This will be described in detail with reference to FIG. First, the software 10 generates an event (ev) and calls gcReq () by the event. Software 10 generates an event at the point where it wants to generate a GC, but this event can include a threshold change. The software 10 outputs gcReq () to the GC generator 14. The GC generator 14 receives gcReq (), calls a method called checkFreeSpace () by gcReq (), and checks the remaining memory size (size). When the process is completed, a process for checking whether the remaining memory amount is equal to or less than a threshold value is selected. When the remaining memory amount is less than or equal to the threshold value in the process, the gc () method is called and a GC is generated by the gc () method.

  The timing at which the software 10 generates an event and outputs a GC request is executed when the UI device 11 after the user selects an application program is executing the process of switching to image display related to the application program, as described above. When the job ends, the software 10 is in an idle state where the software 10 is not operating, the engine device 12 or the IPU device 13 is executing a process, or the UI device 11 is shifted to the power saving mode. it can.

  As a third embodiment of the GC generator 14, the previous (immediate) GC end time is held, and it is confirmed whether the time from the GC end time to the time when the GC request is received is equal to or greater than the threshold. That which generates GC only when is. The GC generator 14 initializes the start time as the GC end time when the apparatus is started, and updates the GC end time when the actual GC ends.

  This will be described in detail with reference to FIG. The software 10 generates an event (ev) in the software 10 when it is desired to generate a GC. The software 10 calls gcReq () when an event occurs, and outputs gcReq () as a GC request to the GC generator 14. The GC generator 14 takes out the previous GC end time (GCTime) held, calculates the time from the GC end time to the time (currentTime) when the gcReq () is received, and the time is equal to or greater than the threshold (criterion). Select the process to check whether or not. If the threshold value is equal to or greater than the threshold in the processing, the GC generator 14 calls the gc () method and generates a GC by the gc () method.

  Also in this case, the timing at which the software 10 generates an event and outputs a GC request is the time when the UI device 11 after the user selects an application program is executing a process of switching to image display related to the application program. Either when the execution job ends, when the software 10 is in an idle state where the engine device 12 and the IPU device 13 are executing processing, or when the UI device 11 shifts to the power saving mode Can do.

  As a fourth embodiment of the GC generator 14, there is one that counts the number of execution jobs every time a GC request is received from the end of the previous GC, and generates a GC when the number of execution jobs exceeds a threshold value. The GC generator 14 holds the counted number of execution jobs, and clears the number of execution jobs to 0 when the GC ends.

  Referring to FIG. 9, the software 10 generates an event (ev) at the time when it is desired to generate a GC, calls gcReq () when the event occurs, and outputs it to the GC generator 14. The GC generator 14 calls jobCount () every time gcReq () is received, and counts the number of execution jobs. Further, the GC generator 14 selects a process for confirming whether the counted number of execution jobs (jobcount) is equal to or greater than a threshold (criterion). The GC generator 14 calls the gc () method when the number of execution jobs exceeds the threshold in the process, and generates a GC by the gc () method. After the GC ends, the GC generator 14 calls clearJobCount (), clears the number of held execution jobs to 0, and ends the process.

  Also in this case, when the UI device 11 after the user selects an application program is executing a process of switching to image display related to the application program, at the end of the execution job, in the idle state where the software 10 is not operating. In addition, when the engine device 12 and the IPU device 13 are executing processing, the UI device 11 can be set to any one of the transition to the power saving mode.

  In the present invention, it is possible to provide a method for suppressing performance degradation due to the occurrence of GC and a GC generation program for realizing this method. This program can be provided by being stored in a recording medium readable by the image forming apparatus. Examples of the recording medium include CD-ROM, CD-RW, MD, DVD-ROM, DVD-RW, DVD-RAM, and flash memory.

  In the above method, when the UI device 11 after the user selects an application program is executing processing for switching to image display related to the application program, when the execution job is finished, the software 10 is idle. A step of outputting a GC request at a predesignated timing such as when the engine device 12 and the IPU device 13 are executing processing and when the UI device 11 has shifted to the power saving mode, Generating GC in response to receiving.

  The present invention has been described with the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and other embodiments, additions, modifications, deletions, and the like can be conceived by those skilled in the art. It can be changed within the range, and any embodiment is included in the scope of the present invention as long as the effects and effects of the present invention are exhibited. Therefore, although four timings are illustrated as timings for generating GC, the timings are not limited to these four timings as long as the operations and effects of the present invention are achieved.

1 is a diagram illustrating a configuration example of a conventional image forming apparatus. 1 is a first sequence diagram illustrating a configuration and a processing flow of an image forming apparatus according to an embodiment. FIG. 6 is a first timing diagram of GC generation in the image forming apparatus of the present embodiment. FIG. 6 is a second timing diagram of GC generation in the image forming apparatus of the present embodiment. FIG. 10 is a third timing diagram of GC generation in the image forming apparatus of the present embodiment. FIG. 10 is a fourth timing diagram of GC generation in the image forming apparatus of the present embodiment. FIG. 6 is a second sequence diagram illustrating the configuration and processing flow of the image forming apparatus according to the present exemplary embodiment. FIG. 10 is a third sequence diagram illustrating the configuration and processing flow of the image forming apparatus according to the present exemplary embodiment. FIG. 10 is a fourth sequence diagram illustrating the configuration and processing flow of the image forming apparatus according to the present exemplary embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Software, 11 ... UI device, 12 ... Engine device, 13 ... IPU device, 14 ... GC generator

Claims (11)

An image forming apparatus having a garbage collection (GC) function for collecting and reusing a memory area that is no longer needed among memory areas to which a program is allocated,
Job execution means for executing a job by executing the program and outputting a GC request at a timing specified in advance;
An image forming apparatus comprising: a GC generation unit that generates a GC in response to reception of the GC request.   The timing is a process performed by a hardware device provided in the image forming apparatus when the image display is switched by a display device provided in the image forming apparatus, at the end of the job, in an idle state where the job execution unit is not operating. The image forming apparatus according to claim 1, wherein the image forming apparatus is at the time of execution or when the display device is shifted to a power saving mode.   The image forming apparatus according to claim 1, wherein the GC generation unit checks the remaining memory amount and generates the GC when the remaining memory amount is equal to or less than a threshold value.   3. The image according to claim 1, wherein the GC generation unit retains a previous GC end time, and generates the GC when a time from the GC end time to reception of the GC request is equal to or greater than a threshold value. 4. Forming equipment.   3. The GC generation unit according to claim 1, wherein the GC generation unit counts the number of execution jobs every time the GC request is received from the end of the previous GC, and generates the GC when the number of execution jobs exceeds a threshold value. The image forming apparatus described. Method for suppressing performance degradation due to occurrence of GC in an image forming apparatus having a garbage collection (GC) function that collects and reuses a memory area that is no longer needed among memory areas to which a program is allocated Because
An execution means for executing a job by executing the program outputs a GC request at a predetermined timing;
Responsive to receiving the GC request, the GC generating means generating a GC.   The timing is a process performed by a hardware device provided in the image forming apparatus when the image display is switched by a display device provided in the image forming apparatus, at the end of the job, in an idle state where the job execution unit is not operating. The method according to claim 6, wherein at the time of execution, the display device is at a transition to a power saving mode.   The method according to claim 6 or 7, wherein in the step of generating GC, a remaining memory amount is examined, and the GC is generated when the remaining memory amount is equal to or less than a threshold value.   The method according to claim 6 or 7, wherein, in the step of generating the GC, the GC is generated when a time from the previous GC end time to the reception of the GC request is equal to or greater than a threshold value.   The step of generating the GC counts the number of execution jobs every time the GC request is received from the end of the previous GC, and generates the GC when the number of execution jobs exceeds a threshold value. 8. The method according to 7.   A GC generation program readable by an image forming apparatus for implementing the method according to claim 6.

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