JP2762467B2 - Computer system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a computer system having a garbage collection device.

[Conventional technology]

Some conventional computer systems include a garbage collection device that collects garbage, such as data that has become meaningless due to an error or data that has been used, remaining in a memory device. By collecting garbage from the memory device by the garbage collection device, a large empty area is secured in the memory device, and the memory device is effectively used.

[Problems to be solved by the invention]

However, in the above-described conventional computer system, only one garbage collection device is provided in the system, and the garbage collection device executes garbage collection at a high processing speed that does not hinder the interactive operation of the user. As a result, the garbage remaining in the memory device may not be reliably collected.

For this reason, a large amount of garbage remains in the memory device, and the system operation of the computer system is abnormally stopped due to insufficient storage capacity of the memory device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a computer system which solves the above-mentioned drawbacks and can prevent abnormal stop of the system operation by reliably collecting garbage from a memory device.

[Means and actions for solving the problem]

The present invention provides a computer system comprising: a storage device including a plurality of storage areas for storing a predetermined amount of data and a reference count of the data; and a garbage collection device that performs garbage collection of the storage device based on the reference count. In the above, if the reference to the storage area occurs, the number of references to the storage area is added, and if the reference to the storage area disappears, the number of references to the storage area is reduced, and the garbage collection of the storage device is performed. A first garbage collection device that collects a storage area in which the number of references becomes 0 at the time of performing, and resets each number of references of the storage area at the time of performing garbage collection of the storage device, and resets a predetermined storage area. The number of references of each storage area is sequentially added by following the storage areas referenced by the storage areas, and the number of references is maintained at 0 A second garbage collection device for reclaiming the storage area, and a first garbage collection device, which start up the first garbage collection device, monitor the free storage area having a reference count of 0, and cannot store desired write data in the free storage area. In this case, a memory management device for activating the second garbage collection device is provided.

Therefore, when the desired write data is larger than the storage area collected by the first garbage collection device, the second garbage collection device can be activated to secure the storage area.

〔Example〕

Hereinafter, embodiments of a computer system according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a main part showing an embodiment of a computer system according to the present invention. In the figure, the computer system comprises a memory device 11 and a garbage collection device 12
And a memory monitoring device 14.

As shown in FIG. 2, the memory device 11 includes a data section 11a for storing data for each storage area, and a reference counter 11b for storing a counter value described later for each storage area.
And

The garbage collection device 12 counts up a reference counter 11b corresponding to the storage area when a reference to the storage area occurs, and, when the reference to the storage area disappears, a reference corresponding to the storage area. The garbage collection device 13 counts down the counter 11b and collects garbage in the corresponding storage area when the count value becomes "0" .The garbage collection device 13 first resets the count values of all the reference counters 11b to "0". From the root storage area, the storage area being referred to is traced, and the reference counter 11b of the storage area traced in the reference process is counted up. Next, the garbage collection device 13 uses a reference counter.
The garbage in all the storage areas where the count value of 11b is “0” is collected. In the embodiment, the garbage collection device 12 is set to execute the garbage collection at a speed that does not hinder the interactive operation of the user, and the processing speed of the garbage collection device 13 (for example, the access time is 6 seconds). ) Is set to a faster processing speed (for example, access time 30 msec).

The memory monitoring device 14 constantly monitors an empty storage area in which no data is stored in the memory device 11, that is, a storage area in which the count value of the reference counter 11b is “0”. Then, one of the garbage collection device 12 and the garbage collection device 13 is started.

Next, the garbage collection operation in the computer system will be described with reference to the flowchart of FIG.

When the computer system operates (Step 2
0), the memory monitoring device 14 constantly monitors an empty storage area of the memory device 11 (that is, a storage area in which the count value of the reference counter 11b is “0”) and starts the garbage collection device 12. Then, the garbage remaining in the memory device 11 is collected (step 21).

When a new storage area is allocated to an empty storage area of the memory device 11, that is, when there is data to be written, the memory monitoring device 14 stores the empty storage area of the memory device 11 and the data of the data to be written. It is determined whether the data to be written can be stored in an empty storage area of the memory device 11 by comparing the amount (step 22). If the data can be stored, the process is continued for the garbage collection device 12. Let it.

On the other hand, a large amount of garbage that has not been collected by the garbage collection device 12 remains in the memory device 11, and the memory monitoring device 14 that has determined that the data to be written cannot be stored in an empty storage area of the memory device 11, the garbage collection device 12 Is put into a standby state, and instead, the garbage collection device 13 is activated, and garbage not collected by the garbage collection device 12 is collected (step 23).

As a result, the memory device 11 has a large empty storage area, and can store data.

When the garbage collection device 13 finishes the garbage collection process, the memory monitoring device 14 returns to step 20 and executes the steps after this step, that is, puts the garbage collection device 13 into a standby state, and starts the garbage collection device 12 instead. Let it.

In the above embodiment, the garbage collection device
13 (slow garbage collection) executes garbage collection in response to the judgment result of the memory monitoring device 14 when a request for allocating a new storage area to the memory device 11 is made. Without being limited, garbage collection may be executed periodically at a preset timing.

According to the above embodiment, the garbage collection device 12
The garbage that has not been collected by the garbage collector 13 is collected by the garbage collection device 13, so that garbage does not remain in the memory device 11, and the memory device 11 can be used effectively. Moreover, since it is extremely unlikely that the memory device 11 runs out of memory due to accumulation of garbage, abnormal stop of the system operation of the computer system can be minimized.

〔The invention's effect〕

As described above, according to the present invention, garbage remaining in the storage device that has not been collected by the first garbage collection device is configured to be collected by the second garbage collection device. Unnecessary garbage can be reduced, and the storage device can be used effectively.

In addition, since it is extremely unlikely that a large amount of garbage remains in the storage device, it is possible to minimize the abnormal stop of the computer system due to a shortage of memory in the storage device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part showing an embodiment of a computer system according to the present invention, FIG. 2 is a schematic configuration diagram showing a memory device, and FIG. 3 is a garbage collection operation in the computer system shown in FIG. It is a flowchart which shows. 11 ... memory device, 12, 13 ... garbage collection device, 14 ... memory monitoring device.

Claims (1)

(57) [Claims] 1. A computer comprising: a storage device including a plurality of storage areas for storing a predetermined amount of data and a reference count of the data; and a garbage collection device that performs garbage collection of the storage device based on the reference count. In the system, if a reference to the storage area occurs, the number of references to the storage area is added, and if the reference to the storage area disappears, the number of references to the storage area is reduced, and the garbage collection of the storage device is performed. A garbage collection device that collects a storage area in which the number of references becomes 0 at the time of performing the garbage collection;
The number of references of the storage area is reset, the storage area sequentially referred to by the storage area is sequentially traced from a predetermined storage area, the number of references of each storage area is added, and the storage area in which the number of references is maintained at 0 is collected. Activating the first garbage collection device and monitoring the free storage area where the reference count is 0, and if desired write data cannot be stored in the free storage area, A memory management device for activating a second garbage collection device.