CODEWITHSUNDEEP
javacross-platformipcshared-memory
Sergey
Sergey

Reputation: 645

Is there a portable shared memory mechanism in Java?

We are looking for a shared memory mechanism to transfer large amounts of data between processes without copying, in Java. It has to be portable (including Windows). Is there such a thing? We were thinking about using mmap-ed files, as they are portable, however their contents are written to disk which is not desirable. Are there alternatives? Otherwise, Windows has page-file-backed sections; is there an easy way to use these in Java? We are probably ok if we can use some other shared memory mechanism on *nix and those on Windows.

Upvotes: 1

Views: 363

Answers (1)

Peter Lawrey
Peter Lawrey

Reputation: 533720

There is a couple of solutions in OpenHFT. These support a rolling queue which can read and written to concurrently, and a SharedHashMap which is entirely off heap. In Linux you can "write" to a tmpfs filesystem and on Windows you can use a Ramdrive.

These libraries support replication between machines over TCP. (The replication for Chronicle has been used for a while but for SharedHashMap, replication is still in beta)

While this is portable across OSes, it uses some features internal to OpenJDK/HotSpot JVMs and so it doesn't work on the IBM JVM AFAIK.

Note: the libraries support reading and writing data using a forma of serialization which doesn't create garbage, or using in place, off heap data structures. i.e. you don't need to deserialize the whole object to access a portion of it.

Upvotes: 1

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