CODEWITHSUNDEEP
javamemorymemory-managementjvm
manurajhada
manurajhada

Reputation: 5390

Multiple Processes under one JVM

Can we run multiple processes in one JVM? And each process should have its own memory quota?

My aim is to start new process when a new http request comes in and assign a separate memory to the process so that each user request has its own memory quota - and doesn't bother other user requests if one's memory quota gets full.

How can I achieve this?

Not sure if this is hypothetical.

Upvotes: 2

Views: 5344

Answers (2)

Tarik
Tarik

Reputation: 11209

The closest concept is Application Isolation API (JSR-121) that AFAIK has not been implemented: See https://en.wikipedia.org/wiki/Application_Isolation_API.

"The Application Isolation API (JSR 121) provides a specification for isolating and controlling Java application life cycles within a single Java Virtual Machine (JVM) or between multiple JVMs. An isolated computation is described as an Isolate that can communicate and exchange resource handles (e.g. open files) with other Isolates through a messaging facility."

See also https://www.flux.utah.edu/janos/jsr121-internal-review/java/lang/isolate/package-summary.html:

"Informally, isolates are a construct midway between threads and JVMs. Like threads, they can be used to initiate concurrent execution. Like JVMs, they cause execution of a "main" method of a given class to proceed within its own system-level context, independently of any other Java programs that may be running. Thus, isolates differ from threads by guaranteeing lack of interference due to sharing statics or per-application run-time objects (such as the AWT thread and shutdown hooks), and they differ from JVMs by providing an API to create, start, terminate, monitor, and communicate with these independent activities."

Upvotes: 1

GhostCat
GhostCat

Reputation: 140613

Short answer: not really.

The Java platform offers you two options:

  1. Threads. And that is the typical answer in many cases: each new incoming request is dealt with by a separate thread (which is probably coming out of a pool to limit the overall number of thread instances that get created/used in parallel). But of course: threads exist in the same process; there is no such thing as controlling the memory consumption "associated" by what a thread is doing.
  2. Child processes. You can create a real process and use that to run whatever you intend to run. But of course: then you have an external real process to deal with.

So, in essence, the real answer is: no, you can't apply this idea to Java. The "more" Java solution would be to look into concepts such as application servers, for example Tomcat or WebSphere.

Or, if you insist on doing things manually; you could build your own "load balancer"; where you have one client-facing JVM; which simply "forwards" requests to one of many other JVMs; and those "other" JVMs would work independently; each running in its own process; which of course you could then "micro manage" regarding CPU/memory/... usage.

Upvotes: 6

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