Computer system with two heaps in contiguous storage

A computer system comprising:

• an information storage subsystem comprising a contiguous linear portion which is logically divided into first and second heaps located at opposite ends of the storage portion subsystem, with any gap between the two heaps representing an unallocated region of storage, wherein references are permitted from objects on the first heap to objects on the second heap and vice versa;
• a garbage collector for operating across both heaps to remove objects that are no longer live;
• a processor configured for expanding the first heap into the unallocated region according to a first expansion policy and for expanding the second heap into the unallocated region according to a second expansion policy;
• and
• a transaction processing environment, wherein the first heap is used for storing objects that are deleted at the end of the current transaction, and the second heap is used for storing objects that persist from one transaction to another;
• and wherein the first heap is reset to the same predetermined initial size at the start of each transaction, and a midpoint is defined halfway between the first heap and the second heap, when each heap has its initial size;
• the first expansion policy is always to expand into the unallocated region in order to satisfy a storage request;
• and the rate of expansion of the first heap into the unallocated region is slower once the first heap has passed the midpoint.

A computer system comprising:

• an information storage subsystem comprising a contiguous linear portion which is logically divided into first and second heaps located at opposite ends of the storage portion subsystem, with any gap between the two heaps representing an unallocated region of storage, wherein references are permitted from objects on the first heap to objects on the second heap and vice versa;
• a garbage collector for operating across both heaps to remove objects that are no longer live;
• a processor configured for expanding the first heap into the unallocated region according to a first expansion policy and for expanding the second heap into the unallocated region according to a second expansion policy;
• and
• a transaction processing environment, wherein the first heap is used for storing objects that are deleted at the end of the current transaction, and the second heap is used for storing objects that persist from one transaction to another;
• and
• wherein the first heap is reset to the same predetermined initial size at the start of each transaction, the processor is structured to return an error condition if the second heap has expanded such that it is not possible to reset the first heap to its predetermined initial size, and the second expansion policy is to expand into the unallocated region in order to satisfy a storage request until the midpoint is reached, whereupon the system preferentially performs a garbage collection to satisfy the request.

A computer system comprising:

• an information storage subsystem comprising a contiguous linear portion which is logically divided into first and second heaps located at opposite ends of the storage portion subsystem, with any gap between the two heaps representing an unallocated region of storage, wherein references are permitted from objects on the first heap to objects on the second heap and vice versa;
• a garbage collector for operating across both heaps to remove objects that are no longer live;
• a processor configured for expanding the first heap into the unallocated region according to a first expansion policy and for expanding the second heap into the unallocated region according to a second expansion policy;
• and
• a transaction processing environment, wherein the first heap is used for storing objects that are deleted at the end of the current transaction, and the second heap is used for storing objects that persist from one transaction to another;
• and
• wherein the first heap is reset to the same predetermined initial size at the start of each transaction, and
• the processor is structured to return an error condition if the second heap has expanded such that it is not possible to reset the first heap to its predetermined initial size, wherein the second expansion policy further includes trying to shrink the first heap to allow room to expand the second heap in order to satisfy a storage request.

A method of operating a computer system providing an object-based environment, the computer system including storage, a contiguous linear portion of which is logically divided into first and second heaps located at opposite ends of the storage portion, with any gap between the two heaps representing an unallocated region of storage, wherein references are permitted from objects on the first heap to objects on the second heap and vice versa, the method comprising steps of:

• operating a garbage collector across both heaps to remove objects that are no longer live;
• expanding the first heap into the unallocated region according to a first expansion policy;
• expanding the second heap into the unallocated region according to a second expansion policy;
• supporting a transaction processing environment wherein the first heap is used for storing objects that are deleted at the end of the current transaction, and the second heap is used for storing objects that persist from one transaction to another;
• resetting the first heap to the same predetermined initial size at the start of each transaction;
• and
• returning an error condition if the second heap has expanded such that it is not possible to reset the first heap to its predetermined initial size.

A computer program product comprising program instructions recorded on a storage medium readable by a computer system, the computer system providing an object-based environment and including storage, a contiguous linear portion of which is logically divided into first and second heaps located at opposite ends of the storage portion, with any gap between the two heaps representing an unallocated region of storage, wherein references are permitted from objects in the first heap to objects in the second heap and vice versa, the program instructions causing the computer system to perform the steps of:

• operating a garbage collector across both heaps to remove objects that are no longer live;
• expanding the first heap into the unallocated region according to a first expansion policy;
• for expanding the second heap into the unallocated region according to a second expansion policy;
• wherein the computer system supports a transaction processing environment, and the first heap is used for storing objects that are deleted at the end of the current transaction, the second heap is used for storing objects that persist from one transaction to another, the first heap is reset to the same predetermined initial size at the start of each transaction, and the system returns an error condition if the second heap has expanded such that it is not possible to reset the first heap to its predetermined initial size.