Status: New
Owner: ----
New issue 2028 by [email protected]: garbage collection issue
http://code.google.com/p/v8/issues/detail?id=2028
// Suggest you copy this page into a JS editor to read.
// @Part1, This part is the API implementation code:
require.define('apis', function (require, module, exports) {
var _history = db.retriveObject(), //db is defined at other place
_listener = {},
_handler,
_self;
_self = {
find: function (successCB, filter) {
var filterResults = _history; // key place! It will work well
if I use utils.copy(_history);
if (filter) {
filterResults = filter(filterResults);
}
setTimeout(successCB(filterResults), 1);
},
addListener: function (observerObj) {
_handler = Math.uuid(null, 16);
_listener[handle] = observerObj;
}
};
event.on("newItems", function (items) {
var observerObj = _listener[_handler];
_history.push(items);
observerObj(items);
});
return _self;
});
// @Part2, The demo code:
var _historyList;
function successCB(results) {
_historyList = results;
}
function addedCB(newItems) {
console.log(_historyList); // New items have been added into
_historyList already here!
_historyList = _historyList.concat(newItems);
}
apis.find(successCB, filter);
apis.addListener(addedCB);
// Problem description:
// In the addedCB function, when it's called for the fist time,
// the newItems will be in the _historyList before it's added! But after
that, when the addedCB
// is called for the second time, no such thing happens.
// Some findings that related:
// After some debugging, I found that the "_historyList" variable in demo
application has pointed
// to the "_history" in apis module for the first time the addedCB is
called. There is a connection
// between "_historyList" in demo and "_history" in the API module.
// The reason and problem that I guess:
// I guess that "filterResults" will be cleared automatically when the
programme exit from "find"
// function, but as it points to "_history", it won't be cleared
immediately, it will be cleared
// automatically only when the "_history" changes.
// The problem is here: When the "_history" changes, all the local
variables that point to
// it should be cleared in the memory, but this should be done
before "_history" changes, not after,
// they may mistake the order so that before those variables are cleared,
they got the new values and
// those values are passed to any variable that points to it. For the
second time it's called, the
// connection has been broke so the "_historyList" in the demo won't get
the latest value of "_history"
// in API module.
// As I am not familiar with the source code of V8, so the location of the
problem has not been found in
// the source code. Here I just report it and expect some expert to confirm
it.
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