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always empty domain stack when handling exceptions #4621

Closed
wants to merge 1 commit into from

2 participants

@cxreg

Re-filing PR #4557 based against master

Make domains a little safer by avoiding potentially unbounded stack bloat

The following code will cause the stack to grow:

var d = require("domain");

setTimeout(function() {
    console.log('domain stack length is now ' + d._stack.length);
}, 100);

d.create().run(function() {
    d.create().run(function() {
        d.create().run(function() {
            d.create().on("error", function(e) {
                console.log("caught " + e)
            }).run(function() {
                    throw new Error("died")
            })
        })
    })
})
@cxreg cxreg referenced this pull request
Closed

Domain stack fixes #4557

@cxreg cxreg always empty domain stack when handling exceptions
Due to the nature of asyncronous programming, it's impossible to know
what will run on the next tick.  Because of this, it's not correct to
maintain domain stack state between ticks

Since the _fatalException handler is only invoked after the stack is
unwound, once it exits the tick will end.  The only reasonable thing to
do in that case is to exit *all* domains.
6f44836
@isaacs
Owner

Landed with slight style change on 14c911d. (Prefer camelCase to snake_case in general. Exceptions made for module names, like var child_process = require('child_process').)

@isaacs isaacs closed this
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Commits on Jan 18, 2013
  1. @cxreg

    always empty domain stack when handling exceptions

    cxreg authored cxreg committed
    Due to the nature of asyncronous programming, it's impossible to know
    what will run on the next tick.  Because of this, it's not correct to
    maintain domain stack state between ticks
    
    Since the _fatalException handler is only invoked after the stack is
    unwound, once it exits the tick will end.  The only reasonable thing to
    do in that case is to exit *all* domains.
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Showing with 50 additions and 1 deletion.
  1. +8 −1 src/node.js
  2. +42 −0 test/simple/test-domain-nested.js
View
9 src/node.js
@@ -243,7 +243,14 @@
// If caught is false after this, then there's no need to exit()
// the domain, because we're going to crash the process anyway.
caught = domain.emit('error', er);
- domain.exit();
+
+ // Exit all domains on the stack. Uncaught exceptions end the
+ // current tick and no domains should be left on the stack between
+ // ticks. Since a domain exists, this require will not be loading
+ // it for the first time and should be safe.
+ var domain_module = NativeModule.require('domain');
+ domain_module._stack.length = 0;
+ domain_module.active = process.domain = null;
} catch (er2) {
caught = false;
}
View
42 test/simple/test-domain-nested.js
@@ -0,0 +1,42 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
+// Make sure that the nested domains don't cause the domain stack to grow
+
+var assert = require('assert');
+var domain = require('domain');
+
+process.on('exit', function(c) {
+ assert.equal(domain._stack.length, 0);
+});
+
+domain.create().run(function() {
+ domain.create().run(function() {
+ domain.create().run(function() {
+ domain.create().on("error", function(e) {
+ // Don't need to do anything here
+ }).run(function() {
+ throw new Error("died")
+ })
+ })
+ })
+})
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