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Bug 738011 - Separate "detached" from "ghost" windows in about:memory. r=njn,mccr8

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--HG--
extra : rebase_source : 5194c9062cdfcd215ce5d708b1b472cf5ba7f480
This commit is contained in:
Justin Lebar 2012-04-02 10:37:04 -04:00
parent a450534b41
commit f5815cc539
3 changed files with 383 additions and 69 deletions
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305
dom/base/nsWindowMemoryReporter.cpp
View File

@ -37,26 +37,46 @@
#include "nsWindowMemoryReporter.h"
#include "nsGlobalWindow.h"
#include "nsIEffectiveTLDService.h"
#include "mozilla/Services.h"
#include "mozilla/Preferences.h"
#include "nsNetCID.h"
#include "nsPrintfCString.h"
using namespace mozilla;
nsWindowMemoryReporter::nsWindowMemoryReporter()
: mCheckForGhostWindowsCallbackPending(false)
{
mDetachedWindows.Init();
}
NS_IMPL_ISUPPORTS1(nsWindowMemoryReporter, nsIMemoryMultiReporter)
NS_IMPL_ISUPPORTS3(nsWindowMemoryReporter, nsIMemoryMultiReporter, nsIObserver,
nsSupportsWeakReference)
/* static */
void
nsWindowMemoryReporter::Init()
{
// The memory reporter manager is going to own this object.
NS_RegisterMemoryMultiReporter(new nsWindowMemoryReporter());
nsWindowMemoryReporter *reporter = new nsWindowMemoryReporter();
NS_RegisterMemoryMultiReporter(reporter);
nsCOMPtr<nsIObserverService> os = services::GetObserverService();
if (os) {
// DOM_WINDOW_DESTROYED_TOPIC announces what we call window "detachment",
// when a window's docshell is set to NULL.
os->AddObserver(reporter, DOM_WINDOW_DESTROYED_TOPIC, /* weakRef = */ true);
}
}
static void
AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr)
static already_AddRefed<nsIURI>
GetWindowURI(nsIDOMWindow *aWindow)
{
nsCOMPtr<nsIDocument> doc = do_QueryInterface(aWindow->GetExtantDocument());
nsCOMPtr<nsPIDOMWindow> pWindow = do_QueryInterface(aWindow);
NS_ENSURE_TRUE(pWindow, NULL);
nsCOMPtr<nsIDocument> doc = do_QueryInterface(pWindow->GetExtantDocument());
nsCOMPtr<nsIURI> uri;
if (doc) {
@ -64,13 +84,25 @@ AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr)
}
if (!uri) {
nsIPrincipal *principal = aWindow->GetPrincipal();
nsCOMPtr<nsIScriptObjectPrincipal> scriptObjPrincipal =
do_QueryInterface(aWindow);
NS_ENSURE_TRUE(scriptObjPrincipal, NULL);
nsIPrincipal *principal = scriptObjPrincipal->GetPrincipal();
if (principal) {
principal->GetURI(getter_AddRefs(uri));
}
}
return uri.forget();
}
static void
AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr)
{
nsCOMPtr<nsIURI> uri = GetWindowURI(aWindow);
if (uri) {
nsCString spec;
uri->GetSpec(spec);
@ -82,6 +114,8 @@ AppendWindowURI(nsGlobalWindow *aWindow, nsACString& aStr)
aStr += spec;
} else {
// If we're unable to find a URI, we're dealing with a chrome window with
// no document in it (or somesuch), so we call this a "system window".
aStr += NS_LITERAL_CSTRING("[system]");
}
}
@ -91,68 +125,31 @@ NS_MEMORY_REPORTER_MALLOC_SIZEOF_FUN(DOMStyleMallocSizeOf, "windows")
static nsresult
CollectWindowReports(nsGlobalWindow *aWindow,
nsWindowSizes *aWindowTotalSizes,
nsTHashtable<nsUint64HashKey> *aGhostWindowIDs,
nsIMemoryMultiReporterCallback *aCb,
nsISupports *aClosure)
{
// DOM window objects fall into one of three categories:
// - "active" windows are currently either displayed in an active
// tab, or a child of such a window.
// - "cached" windows are in the fastback cache.
// - "other" windows are closed (or navigated away from w/o being
// cached) yet held alive by either a website or our code. The
// latter case may be a memory leak, but not necessarily.
//
// For each window we show how much memory the window and its
// document, etc, use, and we report those per URI, where the URI is
// the document URI, if available, or the codebase of the principal in
// the window. In the case where we're unable to find a URI we're
// dealing with a chrome window with no document in it (or somesuch),
// and for that we make the URI be the string "[system]".
//
// Outer windows are lumped in with inner windows, because the amount
// of memory used by outer windows is small.
//
// The path we give to the reporter callback for "active" and "cached"
// windows (both inner and outer) is as follows:
//
// explicit/window-objects/top(<top-outer-uri>, id=<top-outer-id>)/<category>/window(<window-uri>)/...
//
// The path we give for "other" windows is as follows:
//
// explicit/window-objects/top(none)/window(<window-uri>)/...
//
// Where:
// - <category> is "active" or "cached", as described above.
// - <top-outer-id> is the window id (nsPIDOMWindow::WindowID()) of
// the top outer window (i.e. tab, or top level chrome window).
// - <top-inner-uri> is the URI of the top outer window. Excepting
// special windows (such as browser.xul or hiddenWindow.html) it's
// what the address bar shows for the tab.
// - <window-uri> is the URI of aWindow.
//
// Exposing the top-outer-id ensures that each tab gets its own
// sub-tree, even if multiple tabs are showing the same URI.
nsCAutoString windowPath("explicit/window-objects/");
// Our window should have a null top iff it has a null docshell.
MOZ_ASSERT(!!aWindow->GetTop() == !!aWindow->GetDocShell());
nsGlobalWindow *top = aWindow->GetTop();
windowPath += NS_LITERAL_CSTRING("top(");
if (top) {
windowPath += NS_LITERAL_CSTRING("top(");
AppendWindowURI(top, windowPath);
windowPath += NS_LITERAL_CSTRING(", id=");
windowPath.AppendInt(top->WindowID());
} else {
windowPath += NS_LITERAL_CSTRING("none");
}
windowPath += NS_LITERAL_CSTRING(")/");
nsIDocShell *docShell = aWindow->GetDocShell();
if (docShell) {
MOZ_ASSERT(top, "'cached' or 'active' window lacks a top window");
windowPath += aWindow->IsFrozen() ? NS_LITERAL_CSTRING("cached/")
: NS_LITERAL_CSTRING("active/");
} else {
MOZ_ASSERT(!top, "'other' window has a top window");
if (aGhostWindowIDs->Contains(aWindow->WindowID())) {
windowPath += NS_LITERAL_CSTRING("top(none)/ghost/");
} else {
windowPath += NS_LITERAL_CSTRING("top(none)/detached/");
}
}
windowPath += NS_LITERAL_CSTRING("window(");
@ -233,12 +230,20 @@ nsWindowMemoryReporter::CollectReports(nsIMemoryMultiReporterCallback* aCb,
WindowArray windows;
windowsById->Enumerate(GetWindows, &windows);
// Get the IDs of all the "ghost" windows.
nsTHashtable<nsUint64HashKey> ghostWindows;
ghostWindows.Init();
CheckForGhostWindows(&ghostWindows);
nsCOMPtr<nsIEffectiveTLDService> tldService = do_GetService(
NS_EFFECTIVETLDSERVICE_CONTRACTID);
NS_ENSURE_STATE(tldService);
// Collect window memory usage.
nsRefPtr<nsGlobalWindow> *w = windows.Elements();
nsRefPtr<nsGlobalWindow> *end = w + windows.Length();
nsWindowSizes windowTotalSizes(NULL);
for (; w != end; ++w) {
nsresult rv = CollectWindowReports(*w, &windowTotalSizes, aCb, aClosure);
for (PRUint32 i = 0; i < windows.Length(); i++) {
nsresult rv = CollectWindowReports(windows[i], &windowTotalSizes,
&ghostWindows, aCb, aClosure);
NS_ENSURE_SUCCESS(rv, rv);
}
@ -286,4 +291,190 @@ nsWindowMemoryReporter::GetExplicitNonHeap(PRInt64* aAmount)
return NS_OK;
}
NS_IMETHODIMP
nsWindowMemoryReporter::Observe(nsISupports *aSubject, const char *aTopic,
const PRUnichar *aData)
{
// A window was detached. Insert it into mDetachedWindows and run
// CheckForGhostWindows sometime soon.
MOZ_ASSERT(!strcmp(aTopic, DOM_WINDOW_DESTROYED_TOPIC));
void
nsWindowMemoryReporter::ObserveDOMWindowDetached(nsISupports *aWindow)
{
nsWeakPtr weakWindow = do_GetWeakReference(aWindow);
if (!weakWindow) {
NS_WARNING("Couldn't take weak reference to a window?");
return;
}
mDetachedWindows.Put(weakWindow, TimeStamp());
if (!mCheckForGhostWindowsCallbackPending) {
nsCOMPtr<nsIRunnable> runnable =
NS_NewRunnableMethod(this,
&nsWindowMemoryReporter::CheckForGhostWindowsCallback);
NS_DispatchToCurrentThread(runnable);
mCheckForGhostWindowsCallbackPending = true;
}
return NS_OK;
}
void
nsWindowMemoryReporter::CheckForGhostWindowsCallback()
{
mCheckForGhostWindowsCallbackPending = false;
CheckForGhostWindows();
}
struct CheckForGhostWindowsEnumeratorData
{
nsTHashtable<nsCStringHashKey> *nonDetachedDomains;
nsTHashtable<nsUint64HashKey> *ghostWindowIDs;
nsIEffectiveTLDService *tldService;
PRUint32 ghostTimeout;
TimeStamp now;
};
static PLDHashOperator
CheckForGhostWindowsEnumerator(nsISupports *aKey, TimeStamp& aTimeStamp,
void* aClosure)
{
CheckForGhostWindowsEnumeratorData *data =
static_cast<CheckForGhostWindowsEnumeratorData*>(aClosure);
nsWeakPtr weakKey = do_QueryInterface(aKey);
nsCOMPtr<nsIDOMWindow> window = do_QueryReferent(weakKey);
if (!window) {
// The window object has been destroyed. Stop tracking its weak ref in our
// hashtable.
return PL_DHASH_REMOVE;
}
nsCOMPtr<nsIDOMWindow> top;
window->GetTop(getter_AddRefs(top));
if (top) {
// The window is no longer detached, so we no longer want to track it.
return PL_DHASH_REMOVE;
}
nsCOMPtr<nsIURI> uri = GetWindowURI(window);
nsCAutoString domain;
if (uri) {
// GetBaseDomain works fine if |uri| is null, but it outputs a warning
// which ends up overrunning the mochitest logs.
data->tldService->GetBaseDomain(uri, 0, domain);
}
if (data->nonDetachedDomains->Contains(domain)) {
// This window shares a domain with a non-detached window, so reset its
// clock.
aTimeStamp = TimeStamp();
} else {
// This window does not share a domain with a non-detached window, so it
// meets ghost criterion (2).
if (aTimeStamp.IsNull()) {
// This may become a ghost window later; start its clock.
aTimeStamp = data->now;
} else if ((data->now - aTimeStamp).ToSeconds() > data->ghostTimeout) {
// This definitely is a ghost window, so add it to ghostWindowIDs, if
// that is not null.
if (data->ghostWindowIDs) {
nsCOMPtr<nsPIDOMWindow> pWindow = do_QueryInterface(window);
if (pWindow) {
data->ghostWindowIDs->PutEntry(pWindow->WindowID());
}
}
}
}
return PL_DHASH_NEXT;
}
struct GetNonDetachedWindowDomainsEnumeratorData
{
nsTHashtable<nsCStringHashKey> *nonDetachedDomains;
nsIEffectiveTLDService *tldService;
};
static PLDHashOperator
GetNonDetachedWindowDomainsEnumerator(const PRUint64& aId, nsGlobalWindow* aWindow,
void* aClosure)
{
GetNonDetachedWindowDomainsEnumeratorData *data =
static_cast<GetNonDetachedWindowDomainsEnumeratorData*>(aClosure);
if (!aWindow->GetTop()) {
// This window is detached, so we don't care about its domain.
return PL_DHASH_NEXT;
}
nsCOMPtr<nsIURI> uri = GetWindowURI(aWindow);
nsCAutoString domain;
if (uri) {
data->tldService->GetBaseDomain(uri, 0, domain);
}
data->nonDetachedDomains->PutEntry(domain);
return PL_DHASH_NEXT;
}
/**
* Iterate over mDetachedWindows and update it to reflect the current state of
* the world. In particular:
*
* - Remove weak refs to windows which no longer exist.
*
* - Remove references to windows which are no longer detached.
*
* - Reset the timestamp on detached windows which share a domain with a
* non-detached window (they no longer meet ghost criterion (2)).
*
* - If a window now meets ghost criterion (2) but didn't before, set its
* timestamp to now.
*
* Additionally, if aOutGhostIDs is not null, fill it with the window IDs of
* all ghost windows we found.
*/
void
nsWindowMemoryReporter::CheckForGhostWindows(
nsTHashtable<nsUint64HashKey> *aOutGhostIDs /* = NULL */)
{
nsCOMPtr<nsIEffectiveTLDService> tldService = do_GetService(
NS_EFFECTIVETLDSERVICE_CONTRACTID);
if (!tldService) {
NS_WARNING("Couldn't get TLDService.");
return;
}
nsGlobalWindow::WindowByIdTable *windowsById =
nsGlobalWindow::GetWindowsTable();
if (!windowsById) {
NS_WARNING("GetWindowsTable returned null");
return;
}
nsTHashtable<nsCStringHashKey> nonDetachedWindowDomains;
nonDetachedWindowDomains.Init();
// Populate nonDetachedWindowDomains.
GetNonDetachedWindowDomainsEnumeratorData nonDetachedEnumData =
{ &nonDetachedWindowDomains, tldService };
windowsById->EnumerateRead(GetNonDetachedWindowDomainsEnumerator,
&nonDetachedEnumData);
PRUint32 ghostTimeout =
Preferences::GetUint("memory.ghost_window_timeout_seconds", 60);
// Update mDetachedWindows and write the ghost window IDs into aOutGhostIDs,
// if it's not null.
CheckForGhostWindowsEnumeratorData ghostEnumData =
{ &nonDetachedWindowDomains, aOutGhostIDs, tldService,
ghostTimeout, TimeStamp::Now() };
mDetachedWindows.Enumerate(CheckForGhostWindowsEnumerator,
&ghostEnumData);
}

119
dom/base/nsWindowMemoryReporter.h
View File

@ -39,6 +39,10 @@
#define nsWindowMemoryReporter_h__
#include "nsIMemoryReporter.h"
#include "nsIObserver.h"
#include "nsDataHashtable.h"
#include "nsWeakReference.h"
#include "mozilla/TimeStamp.h"
// This should be used for any nsINode sub-class that has fields of its own
// that it needs to measure; any sub-class that doesn't use it will inherit
@ -61,17 +65,130 @@ public:
size_t mLayoutTextRuns;
};
class nsWindowMemoryReporter: public nsIMemoryMultiReporter
/**
* nsWindowMemoryReporter is responsible for the 'explicit/window-objects'
* memory reporter.
*
* We classify DOM window objects into one of three categories:
*
* - "active" windows, which are displayed in a tab (as the top-level window
* or an iframe),
*
* - "cached" windows, which are in the fastback cache (aka the bfcache), and
*
* - "detached" windows, which have a null docshell. A window becomes
* detached when its <iframe> or tab containing the window is destroyed --
* i.e., when the window is no longer active or cached.
*
* Additionally, we classify a subset of detached windows as "ghost" windows.
* Although ghost windows can happen legitimately (a page can hold a reference
* to a cross-domain window and then close its container), the presence of
* ghost windows is often indicative of a memory leak.
*
* A window is a ghost if it meets the following three criteria:
*
* 1) The window is detached.
*
* 2) There exist no non-detached windows with the same base domain as
* the window's principal. (For example, the base domain of
* "wiki.mozilla.co.uk" is "mozilla.co.uk".) This criterion makes us less
* likely to flag a legitimately held-alive detached window as a ghost.
*
* 3) The window has met criteria (1) and (2) above for at least
* memory.ghost_window_timeout_seconds. This criterion is in place so we
* don't immediately declare a window a ghost before the GC/CC has had a
* chance to run.
*
* nsWindowMemoryReporter observes window detachment and uses mDetachedWindows
* to remember when a window first met criteria (1) and (2). When we generate
* a memory report, we use this accounting to determine which windows are
* ghosts.
*
*
* We use the following memory reporter path for active and cached windows:
*
* explicit/window-objects/top(<top-outer-uri>, id=<top-outer-id>)/<category>/window(<window-uri>)/...
*
* For detached and ghost windows, we use
*
* explicit/window-objects/top(none)/<category>/window(<window-uri>)/...
*
* Where
*
* - <category> is "active", "cached", "detached", or "ghost", as described
* above.
*
* - <top-outer-id> is the window id of the top outer window (i.e. the tab, or
* the top level chrome window). Exposing this ensures that each tab gets
* its own sub-tree, even if multiple tabs are showing the same URI.
*
* - <top-uri> is the URI of the top window. Excepting special windows (such
* as browser.xul or hiddenWindow.html) it's what the address bar shows for
* the tab.
*
*/
class nsWindowMemoryReporter: public nsIMemoryMultiReporter,
public nsIObserver,
public nsSupportsWeakReference
{
public:
NS_DECL_ISUPPORTS
NS_DECL_NSIMEMORYMULTIREPORTER
NS_DECL_NSIOBSERVER
static void Init();
private:
// Protect ctor, use Init() instead.
nsWindowMemoryReporter();
/**
* Get the number of seconds for which a window must satisfy ghost criteria
* (1) and (2) before we deem that it satisfies criterion (3).
*/
PRUint32 GetGhostTimeout();
void ObserveDOMWindowDetached(nsISupports* aWindow);
void ObserveAfterMinimizeMemoryUsage();
/**
* When we observe a DOM window being detached, we enqueue an asynchronous
* event which calls this method. This method then calls
* CheckForGhostWindows.
*/
void CheckForGhostWindowsCallback();
/**
* Iterate over all weak window pointers in mDetachedWindows and update our
* accounting of which windows meet ghost criterion (2).
*
* This method also cleans up mDetachedWindows, removing entries for windows
* which have been destroyed or are no longer detached.
*
* If aOutGhostIDs is non-null, we populate it with the Window IDs of the
* ghost windows.
*
* This is called asynchronously after we observe a DOM window being detached
* from its docshell, and also right before we generate a memory report.
*/
void CheckForGhostWindows(nsTHashtable<nsUint64HashKey> *aOutGhostIDs = NULL);
/**
* Maps a weak reference to a detached window (nsIWeakReference) to the time
* when we observed that the window met ghost criterion (2) above.
*
* If the window has not yet met criterion (2) it maps to the null timestamp.
*
* (Although windows are not added to this table until they're detached, it's
* possible for a detached window to become non-detached, and we won't
* remove it from the table until CheckForGhostWindows runs.)
*/
nsDataHashtable<nsISupportsHashKey, mozilla::TimeStamp> mDetachedWindows;
/**
* True if we have an asynchronous call to CheckForGhostWindows pending.
*/
bool mCheckForGhostWindowsCallbackPending;
};
#endif // nsWindowMemoryReporter_h__

6
modules/libpref/src/init/all.js
View File

@ -3524,6 +3524,7 @@ pref("profiler.entries", 100000);
// Network API
pref("dom.network.enabled", true);
pref("dom.network.metered", false);
#ifdef XP_WIN
// On 32-bit Windows, fire a low-memory notification if we have less than this
// many mb of virtual address space available.
@ -3542,3 +3543,8 @@ pref("memory.low_physical_memory_threshold_mb", 0);
// low_memory_notification_interval_ms.
pref("memory.low_memory_notification_interval_ms", 10000);
#endif
// How long must we wait before declaring that a window is a "ghost" (i.e., a
// likely leak)? This should be longer than it usually takes for an eligible
// window to be collected via the GC/CC.
pref("memory.ghost_window_timeout_seconds", 60);