Oracle America, Inc.

Oracle America, Inc. Formerly Known As Sun Microsystems, Inc.

Jiangli Zhou

Nedim Fresko

Dean R E Long

Dean R Long

Yin Zin Mark Lam

In general, the invention relates to a method. The method includes receiving notification, which includes context information, of a trap. The method further includes accessing, based at least partially upon the context information, a particular instruction that caused the trap, determining, based at least partially upon the context information, a particular address that is to be accessed by the particular instruction, updating a set of log information to indicate accessing of the particular address, causing subsequent accesses of the particular address to not give rise to a trap, after causing subsequent accesses of the particular address to not give rise to a trap, accessing the particular address, after accessing the particular address, causing subsequent accesses of the particular address to give rise to a trap, and causing the particular instruction to not be executed.

Trap-based mechanism for tracking accesses of object class names

A mechanism is disclosed for enabling multiple processes to share the same portion of physical memory. The first time an instance of a process is executed, a list of common components is compiled. The compiled code is then written into a newly created mappable data structure, which is stored into persistent storage. The next time an instance of that process is executed, the mappable data structure is mapped into a portion of the process instance's virtual memory space. This enables the process instance to invoke the compiled code for the common components. Multiple instances of the process may have their virtual memory spaces mapped to the same mappable data structure in this way. Thereafter, it is up to the operating system to load the contents of the mappable data structure into a portion of physical memory, and to ensure that all of the process instances share that physical memory portion.

Mechanism for enabling multiple processes to share physical memory

A mechanism is disclosed for implementing fast locking in a multi-threaded system. This mechanism enables fast locking to be performed even on an operating system platform that does not allow one thread to assign ownership of a lock on a mutex to another thread. In addition, the mechanism performs locking in a manner that ensures priority correctness and is low-memory safe. In one implementation, the priority correctness is achieved by using operating system mutexes to implement locking, and the low-memory safe aspect is achieved by pre-allocating a memory section to each thread. This pre-allocated memory section ensures that a thread will have sufficient memory to obtain a lock, even when a system is in a low-memory state. With this mechanism, it is possible to implement locking in a safe and efficient manner.

Mechanism for implementing thread synchronization in a priority-correct, low-memory safe manner

A trap-based mechanism is provided for gaining greater visibility into the memory usage of a process. To detect and record the memory accesses of a process, a virtual address range (or a plurality of address ranges) of the process is set to a protected status. This address range represents the range of virtual addresses that are to be monitored for access. By setting the address range to a protected status, whenever a memory access (in one implementation, whenever a memory write) is made to a virtual address within that address range, a trap arises. When the trap arises, a trap handler is invoked. When invoked, the trap handler records the virtual address that was accessed. In this manner, the access of the virtual address is detected and recorded without having to add extensive instrumentation code to the process.

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San Jose, CA, United States of America

Jiangli Zhou