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[NREPL-44] Expose JMX MBean to provide list of available nREPL endpoints Created: 06/Aug/13  Updated: 08/Aug/13

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Chas Emerick Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

In a development environment, one often has many nREPL servers running, sometimes more than one per project. This means that it's sometimes difficult to keep track of which ports are associated with which projects / processes, and existing per-project REPL tracking mechanisms (e.g. Leiningen/reply's repl-port file) are generally not up the job.

It would be great if nREPL exposed a JMX MBean that provided information on each active nREPL server, what URL(s) they'll respond to, and perhaps other details (what middleware is installed on each, etc). Clients could then use JMX to discover all of the nREPL servers on a given host, and present that information in tool-appropriate 'connect' dialogs, etc.



 Comments   
Comment by Alan Effrig [ 08/Aug/13 7:50 PM ]

How do you envision clients discover which processes have nREPL servers? How would it work in practice from the client's point of view? Would the client be responsible for knowing the JMX port & associated configuration? Do you envision this feature applying mainly to clients on the local machine or to any number of hosts?

When I've worked with JMX, part of the battle is knowing the proper port and associated JMX configuration for each process so a client knows how to connect, especially with a variety of processes on a given host. It is even more problematic in the cloud with dozens of servers. And then there is the complication that locally one can sometimes use the Attach API, a mechanism that differs from how JMX is accessed remotely. At the risk of thinking too much, is there any other standard discovery mechanism that might be appropriate to share the JMX port & configuration with potential clients? Would some sort of multicast/cluster mechanism work here?





[NREPL-40] Thread leak in clojure.tools.nrepl.transport$fn_transport? Created: 11/Mar/13  Updated: 18/Apr/14

Status: In Progress
Project: tools.nrepl
Component/s: None
Affects Version/s: 0.2.1, 0.2.2
Fix Version/s: 0.2.4

Type: Defect Priority: Major
Reporter: David Lao Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None
Environment:

Windows 7 x64, Oracle JDK 1.7.0.11 x64, clojure 1.4.0



 Description   

When trying out remote eval using your sample in the README, ie

(with-open [conn (repl/connect :port 59258)]
(-> (repl/client conn 1000) ; message receive timeout required
(repl/message {:op "eval" :code "(+ 2 3)"})
repl/response-values))

I'm noticing that hosting process leaking a thread each time the remote eval is called. Jconsole shows a clojure-agent-send-off-pool-xxx thread got spawn as result of the call. The stack appears to be pointing to the "while true" loop inside fn_transport.

java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:458)
java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:359)
java.util.concurrent.SynchronousQueue.put(SynchronousQueue.java:878)
clojure.tools.nrepl.transport$fn_transport$fn__3912.invoke(transport.clj:44)
clojure.core$binding_conveyor_fn$fn__3989.invoke(core.clj:1819)
clojure.lang.AFn.call(AFn.java:18)
java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
java.util.concurrent.FutureTask.run(FutureTask.java:166)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
java.lang.Thread.run(Thread.java:722)

What do you recommend as way to free the thread? I have server code that calls nrepl on behave of client connections and the number of call can pile up fairly quickly.



 Comments   
Comment by David Lao [ 12/Mar/13 3:37 PM ]

Here is my workaround.

— a/src/main/clojure/clojure/tools/nrepl/transport.clj
+++ b/src/main/clojure/clojure/tools/nrepl/transport.clj
@@ -36,12 +36,12 @@
to the 2 or 3 functions provided."
([read write] (fn-transport read write nil))
([read write close]

  • (let [read-queue (SynchronousQueue.)]
  • (future (try
  • (while true
  • (.put read-queue (read)))
  • (catch Throwable t
  • (.put read-queue t))))
    + (let [read-queue (SynchronousQueue.)
    + transport-thread (future (try
    + (while true
    + (.put read-queue (read)))
    + (catch Throwable t
    + (.put read-queue t))))]
    (FnTransport.
    (let [failure (atom nil)]
    #(if @failure
    @@ -51,7 +51,7 @@
    (do (reset! failure msg) (throw msg))
    msg))))
    write
  • close))))
    + (fn [] (close)(future-cancel transport-thread))))))
Comment by Chas Emerick [ 06/Aug/13 5:47 AM ]

Very nice catch. I'd love to have a patch from you; do you have a CA filed? (see http://clojure.org/contributing)

Comment by Chas Emerick [ 18/Apr/14 10:07 AM ]

Ping: did you send in a CA? Would love to apply a patch from you for this.





[NREPL-33] Consider making session and eval functionality more accessible Created: 08/Oct/12  Updated: 18/Nov/12

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: 0.2.0-beta9
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Hugo Duncan Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

ritz re-uses some of nrepl's private functions to avoid duplication. The uses are listed below.

Would it be possible to make these functions public? More subjectively, it might also be worth considering factoring out the session functionality into it's own namespace (including msg and possibly queue-eval), so the functionality is not split across the session middleware and the interruptible-eval middleware.

The debug nrepl server:
https://github.com/pallet/ritz/blob/develop/nrepl/src/ritz/nrepl.clj#L189

This uses clojure.tools.nrepl.middleware.session/create-session and clojure.tools.nrepl.middleware.session/session-out

ritz provides an eval op that tracks source forms:
https://github.com/pallet/ritz/blob/develop/nrepl-middleware/src/ritz/nrepl/middleware/tracking_eval.clj

This uses clojure.tools.nrepl.middleware.interruptible-eval/queue-eval and clojure.tools.nrepl.middleware.interruptible-eval/configure-executor






[NREPL-29] Provide a mechanism for overriding an operation Created: 09/Sep/12  Updated: 18/Apr/14

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: 0.2.0-beta9, 0.2.0-beta10
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Hugo Duncan Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

When specifying middleware, it would be much easier for the user to be able to override a default middleware without having to specify a handler.

For example, if there is a default middleware providing the "complete" operation, the user should be able to just specify their preferred completion middleware, without having to specify all middleware as a handler.

One way to do this might be to check metadata for the provided operations of the specified metadata, and ensure that either the default middleware for that operation is removed, or that the specified middleware takes precendence (which may be simpler when a middleware provides multiple operations).



 Comments   
Comment by Chas Emerick [ 14/Sep/12 7:44 AM ]

Agreed.

Just making sure that the order in which additional middlewares are provided is taken as a default stack order will suffice for most use cases. Transforming middlewares (either in full or in part) would need another metadata slot, :replace perhaps, though it seems like that would be much more difficult to get right.





[NREPL-24] :session key is overloaded Created: 10/Aug/12  Updated: 03/Oct/12

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Hugo Duncan Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

The session middleware takes the :session key from the message, and uses it as an id to lookup session data, which it then places on the same key.

Using a separate key for the session id and the session data would be less confusing, and would allow easier checking of the availability of the session data in the message map.



 Comments   
Comment by Chas Emerick [ 10/Aug/12 11:26 PM ]

The session id will need to continue to come in in the :session slot, as I don't want to break clients (and, there's very, very few middlewares out there yet).

Suggestions for names for the actual session atom? :the-session? :-/





[NREPL-15] Allow clients to specify an ID for newly-retained sessions Created: 29/Mar/12  Updated: 12/Oct/12

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Chas Emerick Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

...particularly important where less sophisticated clients and polling-oriented transports are involved (e.g. HTTP).






[NREPL-4] Provide sane multiplexing of output in the face of multithreaded, asynchronous operation Created: 30/Sep/11  Updated: 03/Oct/12

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Chas Emerick Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

Basically, (send-off some-agent println) & co. should get what's printed to out in that agent's thread back to the nREPL client — not silently let it dump out to System/out.

Portal ostensibly does this well. Examine their approach, see if it is compatible with nREPL's objectives.

Ill-formed brain dump:

  • multiplex new out's to System/out
    • (still won't solve clojure.test/test-out content will disappearing into the ether when it's loaded when out is bound to an nREPL out; maybe we should ensure out is bound to System/out while code is being loaded?)
  • optionally multiplex System/out and System/err
  • optionally join multiplexed S/out and S/err, receive :stdout, :stderr msgs





[NREPL-3] Adopt default port Created: 30/Sep/11  Updated: 22/Oct/12

Status: Open
Project: tools.nrepl
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Chas Emerick Assignee: Chas Emerick
Resolution: Unresolved Votes: 0
Labels: None


 Description   

7888 is "free", at least in IANA.

Most users want to put an nREPL port on their app, and that should always be on a typical port. Auto-selection of a port is only desirable in tooling scenarios, and tooling authors can pass an argument to start-server.

This will change the behaviour of (start-server).






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