Browse Prior Art Database

Object Store Garbage Collection

IP.com Disclosure Number: IPCOM000014250D
Original Publication Date: 2001-Jun-16
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Abstract

Disclosed is a program that has been designed to scan shared ObjectStore files at appropriate intervals, deleting timed-out objects. An ObjectStore file is used to hold the passive state of Java* Bean Objects between OTS transactions. The file is shared across AORs, so a Bean passivated in one region may be activated in another. When a Bean is passivated, we have no way of knowing whether it will ever be activated or removed. Hence we need some clean-up mechanism, wich will prevent the ObjectStore file from filling up with old forgotten Beans. A shared file is divided into logical areas known as ObjectStores, one ObjectStore per logical CorbaServer. The ObjectStore is opened with a timeout value, specifying the period after which objects may be automatically deleted from the store. A control record is written for each ObjectStore containing:

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Object Store Garbage Collection

Disclosed is a program that has been designed to scan shared ObjectStore files at appropriate intervals, deleting timed-out objects.

     An ObjectStore file is used to hold the passive state of Java* Bean Objects between OTS transactions. The file is shared across AORs, so a Bean passivated in one region may be activated in another. When a Bean is passivated, we have no way of knowing whether it will ever be activated or removed. Hence we need some clean-up mechanism, wich will prevent the ObjectStore file from filling up with old forgotten Beans.

     A shared file is divided into logical areas known as ObjectStores, one ObjectStore per logical CorbaServer.

     The ObjectStore is opened with a timeout value, specifying the period after which objects may be automatically deleted from the store. A control record is written for each ObjectStore containing:

     A timestamp giving the time of the last garbage scan, A timeout value giving the interval after which objects may be deleted, A scan interval giving the garbage scan frequency (initially same as timeout value), and Statistics giving results of the previous scan.

     When an OBJECT is stored in an Object Store which was opened with a non-zero timeout value, we check whether garbage_collection is ON in the local system. If not ON, we call the CICS timer to start the garbage_collector after a delay of the ObjectStore timeout value, and set garbage_collection ON.

     When the garbage_collector runs, it sets local delay_interval equals 0, and performs the following six steps on each ObjectStore currently open with a non-zero timeout value on the local system:

1. Read the Object Store Control Record, which contains the time of the last garbage scan and the store scan_interval.
2. If the record indicates that the store scan_interval has expired then update the timestamp to indicate a garbage scan is in progress, else goto next ObjectStore.
3. Browse all object header re...