JP4504756B2 - Memory management method and memory management program in Java (registered trademark) execution environment - Google Patents

Description

The present invention relates to a memory management method and a memory management program in a Java ( registered trademark ) execution environment.

The Java ( registered trademark ) technology developed by Sun Microsystems Co., Ltd. has been developed mainly in the world of the Internet, and then used for the development of server-side Java ( registered trademark ) and application software. It is also used. Java ( registered trademark ) programs used in mobile phones often handle multimedia data such as audio, still images, and moving images. Especially in recent years, the size of these multimedia data tends to increase rapidly as the communication speed increases and the display screen becomes higher in definition.

When such multimedia data is played back or processed, this processing is generally performed by an external native program that is independent of the Java ( registered trademark ) execution environment. Therefore, in this case, a data link operation between the Java ( registered trademark ) execution environment and the native program is required. Here, examples of the native program include a decoder as a reproduction program for audio and moving images, an encoder as a recording program, and a communication protocol stack.

The memory management mechanism provided in the Java ( registered trade name ) execution environment is designed to handle Java ( registered trade name ) objects efficiently, and has a garbage collection function for collecting memory that is no longer used, It has a compaction mechanism to prevent fragmentation.

However, some Java ( registered trademark ) objects managed by such a memory management mechanism may not be managed in the same manner as other Java ( registered trademark ) objects.

For example, when there is a Java ( registered trademark ) object processed by a native program that operates asynchronously with the Java ( registered trademark ) execution environment, if compaction is performed by the memory management mechanism in the middle of processing, processing is performed by compaction. There is a problem that the data inside moves and cannot be read from the native program.

In order to deal with such a problem, when data handled by a Java ( registered trademark ) program is processed by a native program, the heap area allocated for the Java ( registered trademark ) program is used. There is a method of performing processing by a native program after copying to a secured memory area.

In the above method, when the native program updates the data and then returns the processing from the native program to the Java ( registered trademark ) program, the data updated by the native program in order to ensure data consistency. Is copied to the heap area and written back.

As described above, when a process of copying data occurs between the heap area used by the Java ( registered trademark ) program and another memory area used by the native program, a large amount of memory capacity of the system is consumed. At the same time, there arises a problem that processing is delayed by the time required for copying. In particular, when handling audio or moving image data having a large memory size, the memory capacity is extremely large, and the processing delay becomes significant.

The present invention has been made paying attention to such a problem, and an object of the present invention is a memory management mechanism and a memory management program used in a Java ( registered trademark ) execution environment. An object of the present invention is to provide a memory management mechanism and a memory management program capable of efficiently managing even different data, and particularly capable of efficiently linking data with a native program.

In order to achieve the above object, the present inventor has conducted research, and the frequency used from the native program differs depending on the data type of the Java ( registered trademark ) object, in particular, Java [ registered by byte []. It was found that the frequency of using the ( trade name ) object is high from the native program.

The present invention has been made in view of the above knowledge, and the memory management method according to the first invention is a memory management method in a Java ( registered trademark ) execution environment, and is a Java ( registered trademark ) object. When a request for allocating to the heap area occurs, depending on the data type, the Java ( registered trademark ) object is replaced with the first type Java ( registered trademark ) object and the second type Java (registered). (Trademark name) object classification step, and when there is no free space in the first memory area to which the first type Java ( registered trade name ) object is allocated, the first memory area perform first compaction processing, the second type of Java (registered trademark) objects allocated A compaction execution step for executing a second compaction process different from the first compaction process for the second memory area when there is no free space in the second memory area; and the first compaction The first type Java ( registered trademark ) object is allocated to the first memory area that has been freed by processing, and the second memory area has been freed by the second compaction process. an object allocation step of allocating a second type of Java (registered trademark) objects, comprising a.

According to a second invention, in the memory management method according to the first invention, a Java ( registered trademark ) object to which a predetermined mark is assigned is allocated in the second memory area. In the compaction process 2, the compaction process is not performed on the Java ( registered trademark ) object to which the mark is added .

According to a third aspect, in the memory management method according to the second aspect, a predetermined mark is assigned to a Java ( registered trademark ) object used from a native program.

According to a fourth aspect of the present invention, in the memory management method according to any one of the first to third aspects, the second type Java ( registered trademark ) object has a data type of a one-dimensional array of bytes. Have.

The fifth invention is the memory management method according to any one of the first to fourth inventions, wherein the Java ( registered trademark ) object having a one-dimensional array of bytes is audio data, image data or communication. It is data.

A memory management program according to a sixth aspect of the present invention is a memory management program in a Java ( registered trademark ) execution environment for linking data with a native program, and the processing means includes a Java ( registered trademark ). When a request for allocating an object to the heap area occurs, the Java ( registered trademark ) object is replaced with a first type Java ( registered trademark ) object according to the frequency used by the native program. Object classification processing for classifying into two types of Java ( registered trademark ) objects, and the first memory area to which the first type of Java ( registered trademark ) objects are allocated is empty. A first compaction process is performed on one memory area, and the second tag If there is no space in the second memory area flops Java (registered trademark) objects are allocated to this second memory area, a second compaction processing different from the first compaction processing The compaction process to be executed and the first type Java ( registered trademark ) object are allocated to the first memory area where a space is generated by the first compaction process, and the space is generated by the second compaction process. And an object allocation process for allocating the second type Java ( registered trademark ) object in the second memory area where the occurrence of the error occurs.

According to a seventh invention, in the memory management program according to the sixth invention, a Java ( registered trademark ) object to which a predetermined mark is given is allocated in the second memory area. In the compaction process 2, the compaction process is not performed on the Java ( registered trademark ) object to which the mark is added .

In addition, according to an eighth aspect, in the memory management program according to the seventh aspect, a predetermined mark is assigned to a Java ( registered trademark ) object used from a native program.

According to a ninth invention, in the memory management program according to the seventh or eighth invention, the second type Java ( registered trademark ) object has a data type of a one-dimensional array of bytes.

The tenth invention is the memory management program according to any one of the sixth to ninth inventions, wherein the Java ( registered trademark ) object having a one-dimensional array of bytes is audio data, image data or communication data. It is data.

According to the present invention, different compaction processes can be used depending on the data type of the Java ( registered trademark ) object, so that different compaction processes are applied depending on the data type of the object. Therefore, even if there are objects having different forms and properties, memory management can be performed efficiently.

The present invention is particularly applicable to the case where a data type Java ( registered trademark ) object frequently used by a native program and other objects are used in different memory areas to be subjected to different compaction processes. Is preferred. In this case, the Java ( registered trademark ) object used by the native program is not subjected to the compaction process, so that a memory area can be secured and a copy operation can be performed to cope with the object movement during the compaction process. This eliminates the need for data linkage between the Java ( registered trademark ) program and the native program, and enables extremely efficient data linkage.

First, an outline of the present embodiment will be described. In the Java ( registered trademark name ) execution environment, many Java ( registered trademark name ) objects are used only by Java ( registered trademark name ) programs, and when data is linked with native programs, Only a few Java ( registered trademark ) objects are used by the native program. Here, for Java ( registered trademark ) objects used in native programs, it is necessary to cope with address movement by compaction processing, but for other Java ( registered trademark ) objects, such a countermeasure is required. do not do. Therefore, efficient memory operation can be realized by distinguishing and managing them.

The present inventors have Java (registered trademark) and a result of careful observation native program that work, Java utilized by native program (registered trademark) object has a one-dimensional array of byte as the data type in most cases I understood it. Specific examples of Java ( registered trademark ) objects (byte [] objects) having a one-dimensional array of bytes include multimedia data such as audio data and image (including moving image) data, communication data, and the like.

Therefore, in the present embodiment, a normal Java ( registered trademark ) object is classified as a first type Java ( registered trademark ) object, and a byte [] object is classified as a second type Java ( registered trademark ) object. The first type Java ( registered trade name ) object is stored in the first area in the heap area, and the second type Java ( registered trade name ) object is stored in the second area in the heap area. To. Among the byte [] objects in the second area, a Java ( registered trademark ) object used by the native program is a predetermined mark that prohibits movement during compaction processing during data linkage with the native program. Is granted. Here, Java ( registered trademark ) objects that are not moved are locked by setting the mark bit to the ON state. The locked Java ( registered trademark ) object is not subjected to compaction processing as described later, and is not moved. After the data linkage with the native program is completed, the mark bit is turned off and the lock is released.

As a method to distinguish whether to permit or inhibit movement during the compaction process, instead of granting each a predetermined mark on Java (registered trademark) objects, authorization Navigate by Java (registered trademark) objects Alternatively, a management table in which prohibition information is written may be used.

When a request for allocating a new Java ( registered trademark ) object to the heap area occurs, if there is not enough memory area to allocate, garbage collection processing for collecting memory that is no longer used Alternatively, the compaction processing is performed so that the memory areas in use that are finely divided are combined into a continuous memory area. In this case, the first type Java ( registered trademark ) object in which the first type is stored is stored. In this area, all objects are moved by the compaction process, and fragmentation is prevented from occurring. On the other hand, in the compaction process for the second area in which the second type Java ( registered trademark ) object is stored, a different compaction process is executed. That is, the compaction processing here is performed by moving only the other objects without moving the objects that are locked with the mark bit set to the ON state.

Then, a first type Java ( registered trademark ) object is allocated in the first memory area where a space is generated by the compaction process, and a second type is stored in the second memory area where a space is generated by the compaction process. Java ( registered trademark ) objects are allocated.

As described above, in this embodiment, the byte [] object that is frequently used by the native program is arranged in the second memory area, and the mark bit of the object is set while the object is actually used by the native program. Set to ON state. The compaction process for the second memory area does not move the object whose mark bit is in the ON state. Therefore, the object used by the native program is not moved by the compaction process. Therefore, an operation for securing and copying a new memory area outside the heap area in order to cope with object movement by compaction processing becomes unnecessary, thereby enabling efficient data linkage with the native program. In this case, normal compaction processing is performed for objects other than the byte [] object, so that memory management similar to memory management in the conventional Java ( registered trademark ) execution environment is possible.

Memory management (particularly compaction processing) applied to the second memory area involves an overhead because it involves determining whether or not the Java ( registered trademark ) object is locked. Since the memory management is applied, the influence can be reduced.

In addition, Java ( registered trademark name ) objects used from native programs often have a large capacity especially in the case of multimedia data, and such Java ( registered trademark name ) objects have a Java ( registered trademark name ) execution environment. Generation of fragmentation becomes a problem when distributed and locked over the entire heap area. However, in this embodiment, the Java ( registered trademark ) object used from the native is mainly arranged in the second memory area, so even if fragmentation occurs, the influence is limited to the second memory area. Can be.

  Note that when an object other than the byte [] object is used from a native program, such an object must be copied to the outside of the heap area as in the conventional case because it is located in the first memory area. Because the frequency is very low, there is no problem.

In addition, since normal Java ( registered trademark name ) objects and Java ( registered trademark name ) objects that link with native programs have different sizes and lifetime trends, data that is frequently linked with native programs and data that is low The efficiency of memory management is also improved.

In addition, since there is no new extension to the Java ( registered trademark name ) language specification, it is only necessary to modify the Java ( registered trademark ) execution environment, and there is no need to modify existing programs. Affinity with other programs can be maintained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of a hardware configuration for carrying out the present invention. Here, the hardware configuration of an embedded device (for example, a mobile phone) equipped with the Java ( registered trademark ) execution environment of this embodiment is shown. Show. In FIG. 1, a memory 11 is a part for storing various programs and data. The input / output unit 13 serves as a user interface and includes input keys, a microphone, a speaker, and the like. The display unit 12 is a part for displaying information such as various menus and operation statuses. The CPU 10 is a part that controls the operation of each part of the apparatus. The Java ( registered trademark ) object classification function, the memory area compaction function, and the Java ( registered trademark ) object allocation function used in this embodiment are executed when the CPU 10 reads and executes various programs stored in the memory 11. Virtually constructed.

FIG. 2 is an explanatory diagram of a software configuration for carrying out the present invention. As shown in FIG. 2, a VM (Virtual Machine) 24, a class library 22, and a Java ( registered trademark ) application 20 are mounted on the platform (OS and hardware) 23 as a Java ( registered trademark ) execution environment. ing. The VM 24 is a program that is executed while converting a class file in which Java ( registered trademark ) bytecode is stored into native code.

The VM 24 has a Java ( registered trademark name ) heap area 25. As shown in FIG. 3, the VM 24 has a first area 25-1 to which a normal Java ( registered trademark name ) object is allocated, and a byte. [] A second area 25-2 where an object is allocated is provided. Furthermore, native program applications 1 (26) and 2 (27) for performing data linkage (read / write) with the Java ( registered trademark ) execution environment are installed.

FIG. 4 is a flowchart showing a procedure for allocating a Java ( registered trademark ) object by the method of this embodiment.

When a request for allocating a Java ( registered trademark name ) object to the heap area occurs, the CPU 10 determines whether or not the data type of the Java ( registered trademark name ) object is byte [] (step S1). In the case of NO, that is, in the case of a normal Java ( registered trademark name ) object, it is determined whether or not there is an empty space in the first area 25-1 of the Java ( registered trademark ) heap area 25 (step S2). . If the determination here is YES, the Java ( registered trademark ) object is allocated to the first area 25-1 (step S5), and then the process ends.

If the determination in step S2 is NO, garbage collection is performed on the first and second areas 25-1 and 25-2 to release unused areas, and the first area A compaction process for moving the Java ( registered trade name ) object in use in 25-1 is executed (step S3). Next, it is determined whether or not an empty space has been generated in the first area 25-1 by the above garbage collection and compaction processing (step S4). If YES, Java ( registered) is registered in the first area 25-1. (Trade name ) object is allocated (step S5), and then the process ends. On the other hand, if the determination in step S4 is NO, an error message indicating no free space is displayed (step S6), and the process ends.

On the other hand, if the determination in step S1 is YES, it is determined whether or not there is an empty space in the second area 25-2 of the Java ( registered trademark ) heap area 25 (step S7). If the determination here is YES, the Java ( registered trademark ) object is allocated to the second area 25-2 (step S10), and then the process ends.

When the determination in step S7 is NO, garbage collection is performed on the first and second areas 25-1 and 25-2 to release unused areas, and the second area A compaction process for moving only the unlocked Java ( registered trademark ) object in 25-2 is executed (step S8). Next, it is determined whether or not an empty space is generated in the second area 25-2 by the garbage collection and compaction process (step S9). If YES, Java ( registered ) is stored in the second area 25-2. (Trade name ) object is allocated (step S10), and then the process ends. On the other hand, if the determination in step S9 is NO, an error message indicating no free space is displayed (step S6), and the process ends.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, even if a language system that succeeds Java ( registered trademark ) is newly proposed, if the language system assumes memory management such as garbage collection and compaction by the execution environment, the present invention This memory management method and memory management program can be applied in the same manner as in the above embodiment. Moreover, there is no restriction | limiting in the method of garbage collection or compaction, The applicable method can be used suitably. Further, the timing of performing garbage collection and compaction is not limited to the above embodiment, and these may be performed asynchronously with the timing of request generation for allocating a Java ( registered trademark ) object.

It is explanatory drawing of the hardware constitutions for implementing this invention. It is explanatory drawing of the software structure for implementing this invention. It is a figure which shows two area | regions for allocating a Java ( trademark name ) object. It is a flowchart which shows the procedure which allocates a Java ( trademark name ) object by the method of this embodiment.

DESCRIPTION OF SYMBOLS 10 ... CPU, 11 ... Memory, 12 ... Display unit, 13 ... Input / output unit, 20 ... Java ( registered trademark ) application, 21 ... AMS, 22 ... Class library, 23 ... Platform, 24 ... VM, 25 ... Java ( (Registered trademark name ) heap area, 25-1... First area, 25-2... Second area, 26.

Claims (10)

A memory management method in a Java ( registered trademark ) execution environment,
When a request for allocating a Java ( registered trademark name ) object to a heap area occurs, the Java ( registered trademark name ) object is changed to a first type Java object ( registered trademark name ) and a second type according to the data type. An object classification step for classifying into a type of Java ( registered trademark ) object;
If there is no free space in the first memory area to which the first type Java ( registered trademark ) object is allocated, the first compaction process is executed on the first memory area, and the second If there is no free space in the second memory area to which the Java ( registered trademark ) object of this type is allocated, a second compaction process different from the first compaction process is applied to the second memory area. A compaction execution step for executing
The first type Java ( registered trademark ) object is allocated to the first memory area where a space is generated by the first compaction process, and the second space is generated by the second compaction process. an object allocation step of allocating the memory area the second type of Java (registered trademark) objects,
A memory management method. Wherein the second memory area, Java predetermined mark is assigned (registered trademark) objects and is allocated, the second compaction process, Java (registered trademark) in which the mark is assigned object The memory management method according to claim 1, wherein compaction processing is not performed on the memory. 3. The memory management method according to claim 2, wherein a predetermined mark is assigned to a Java ( registered trademark ) object used from a native program. 4. The memory management method according to claim 1, wherein the second type Java ( registered trademark ) object has a data type of a one-dimensional array of bytes. 5. The memory management method according to claim 1, wherein the Java ( registered trademark ) object having a one-dimensional array of bytes is audio data, image data, or communication data. 6. A memory management program in a Java ( registered trademark ) execution environment that performs data linkage with a native program,
In processing means,
When a request for allocating a Java ( registered trademark name ) object to a heap area occurs, the Java ( registered trademark name ) object is changed to a first type Java object ( registered trademark name ) and a second type according to the data type. Object classification processing for classifying into Java ( registered trademark ) objects of the type;
If there is no free space in the first memory area to which the first type Java ( registered trademark ) object is allocated, a first compaction process is executed on the first memory area, and the second If there is no free space in the second memory area to which the Java ( registered trademark ) object of this type is allocated, a second compaction process different from the first compaction process is performed for the second memory area. A compaction process to execute
The first type Java ( registered trademark ) object is allocated to the first memory area where a space is generated by the first compaction process, and the second space is generated by the second compaction process. Object allocation processing for allocating the second type Java ( registered trademark ) object in a memory area of
A memory management program. Wherein the second memory area, Java predetermined mark is assigned (registered trademark) objects and is allocated, the second compaction process, Java (registered trademark) in which the mark is assigned object The memory management program according to claim 6, wherein compaction processing is not performed on the memory. The memory management program according to claim 7, wherein a predetermined mark is assigned to a Java ( registered trademark ) object used from a native program. The memory management program according to any one of claims 6 to 8, wherein the second type Java ( registered trademark ) object has a data type of a one-dimensional array of bytes. 10. The memory management program according to claim 6, wherein the Java ( registered trademark ) object having a one-dimensional array of bytes is audio data, image data, or communication data.

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