Garbage collection method and apparatus
View Patent ↗Disclosed herein are a garbage collection method and apparatus. The garbage collection method includes when an area dynamically allocated through a malloc( ) function or a new operator of a standard C library is deallocated through a free( ) function or a delete operator, inserting the deallocated area into a quarantine list, recording a base address and an end address of each of areas inserted into the quarantine list in a CSR_quarantined_chunks register, finding a physical address of a memory page used by a processor and searching data in the memory page for a value included in a quarantined area of the CSR_quarantined_chunks register, when a value included in the quarantined area is not present, setting a state flag bit of the register to 0, and deleting an area which the state flag bit is 0 from the quarantine list, and inserting the area into a free list.
1 . A garbage collection method, comprising:
deallocating an area dynamically allocated through a malloc function or a new operator of a standard C library through a free function or a delete operator, thereby inserting the deallocated area into a quarantine list;
recording a base address and an end address of each of areas inserted into the quarantine list in a CSR (control and status register)_quarantined_chunks register;
finding a physical address of a memory page used by a processor and searching pieces of data in the memory page for a value included in a quarantined area of the CSR_quarantined_chunks register;
determining a value included in the quarantined area of the CSR_quarantined_chunks register is not present, thereby setting a state flag bit of the CSR_quarantined_chunks register to 0; and
deleting an area which the state flag bit of the CSR_quarantined_chunks register is 0 from the quarantine list, and inserting the area into a free list in which reallocation is enabled,
wherein, to improve search efficiency of dangling pointers, the tag value is configured such that a 1-bit tag value is added for each specific size of a memory or such that a shadow memory is allocated and used as a tag value.
2 . The garbage collection method of claim 1 , wherein the CSR_quarantined_chunks register includes a virtual base address, a virtual end address, and a state flag bit of each quarantined memory area.
3 . The garbage collection method of claim 1 , wherein the state flag bit has a value of 1 in a quarantined state, and is changed to 0 when no dangling pointer is determined to be present.
4 . The garbage collection method of claim 1 , wherein the tag value is initialized to 0 and is set to 1 when a value between values of CSR_HEAP_BASE and CSR_HEAP_END is written to the memory in execution.
5 . The garbage collection method of claim 1 , wherein a tag value of a heap area is initialized to 0 when a specific area is deallocated through a free function.
6 . The garbage collection method of claim 1 , wherein a tag value of a stack area is initialized for a stack area that is no longer used while changing a stack pointer value when a function is returned.
7 . A garbage collection apparatus, comprising:
a memory configured to store a control program for performing garbage collection; and
a processor configured to execute the control program stored in the memory,
wherein the processor is configured to deallocate an area dynamically allocated through a malloc function or a new operator of a standard C library through a free function or a delete operator, insert the deallocated area into a quarantine list, record a base address and an end address of each of areas inserted into the quarantine list in a CSR (control and status register)_quarantined_chunks register, find a physical address of a memory page used by the processor, search pieces of data in the memory page for a value included in a quarantined area of the CSR_quarantined_chunks register, determine a value included in the quarantined area of the CSR_quarantined_chunks register is not present, set a state flag bit of the CSR_quarantined_chunks register to 0, delete an area which the state flag bit of the CSR_quarantined_chunks register is 0 from the quarantine list, and insert the area into a free list in which reallocation is enabled,
wherein, to improve search efficiency of dangling pointers, the processor is configured to perform control such that a 1-bit tag value is added for each specific size of a memory or such that a shadow memory is allocated and used as a tag value.
8 . The garbage collection apparatus of claim 7 , wherein the CSR_quarantined_chunks register includes a virtual base address, a virtual end address, and a state flag bit of each quarantined memory area.
9 . The garbage collection apparatus of claim 7 , wherein the processor is configured to control the state flag bit such that the state flag bit has a value of 1 in a quarantined state and is changed to 0 when no dangling pointer is determined to be present.
10 . The garbage collection apparatus of claim 7 , wherein the processor is configured to perform control such that the tag value is initialized to 0 and is set to 1 when a value between values of CSR_HEAP_BASE and CSR_HEAP_END is written to the memory in execution.
11 . The garbage collection apparatus of claim 7 , wherein the processor is configured to perform control such that a tag value of a heap area is initialized to 0 when a specific area is deallocated through a free function.
12 . The garbage collection apparatus of claim 7 , wherein the processor is configured to perform control such that a tag value of a stack area is initialized for a stack area that is no longer used while changing a stack pointer value when a function is returned.