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[SR-5256] Memory leak with Foundation XMLNode.nodes(forXPath:) #4287

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swift-ci opened this issue Jun 19, 2017 · 3 comments
Closed

[SR-5256] Memory leak with Foundation XMLNode.nodes(forXPath:) #4287

swift-ci opened this issue Jun 19, 2017 · 3 comments
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bug Foundation Linux

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@swift-ci
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Previous ID SR-5256
Radar None
Original Reporter djones6 (JIRA User)
Type Bug
Status Resolved
Resolution Done
Environment

Ubuntu 14.04, tried with both Swift 3.1.1 + 4.0-2017-06-12a snapshot

Additional Detail from JIRA
Votes 1
Component/s Foundation
Labels Bug, Linux
Assignee mattrajca (JIRA)
Priority Medium

md5: d135788b67f892d4da8ac6fd1d4c05fc

Issue Description:

The following code leaks on Linux:

import Foundation
let path = FileManager.default.currentDirectoryPath.appending("/sample.xml")
let xml = try! XMLDocument(contentsOf: URL(fileURLWithPath: path), options: [])
let node = try! xml.nodes(forXPath: "/items/item[@id='1']").first!
while true {
    do {
        _ = try node.nodes(forXPath: "@id").first!.stringValue!
    } catch {
        exit(1)
    }
}

Here's the input document:

<?xml version="1.0" encoding="utf-8"?>
<items><item id="1">Some text</item></items>

Running through valgrind indicates that allocations as a result of _CFXMLNodesForXPath -> xmlXPathNewContext -> xmlHashCreate (libxml2) are never freed. Here's what happens if I let the above loop run 200,000 times:

valgrind --tool=massif ./xmlLeak_sr
ms_print massif.out.<pid> | swift-demangle | less
...
    GB
2.484^                                                                       #
     |                                                                     @@#
     |                                                                 ::::@@#
     |                                                             @@::::: @@#
     |                                                         @@@@@@: ::: @@#
     |                                                      @@@@ @@@@: ::: @@#
     |                                                    @@@@@@ @@@@: ::: @@#
     |                                                @@@@@@@@@@ @@@@: ::: @@#
     |                                            ::@@@ @ @@@@@@ @@@@: ::: @@#
     |                                       :::::: @ @ @ @@@@@@ @@@@: ::: @@#
     |                                    @@@: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |                                 @@@@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |                             ::::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |                         @@@:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |                       ::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |                  @@@@@::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |               @@:@@ @ ::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |            @@@@ :@@ @ ::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |       @@@::@@@@ :@@ @ ::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
     |    @@@@ @: @@@@ :@@ @ ::@ @:: ::@ @@ @: :: : @ @ @ @@@@@@ @@@@: ::: @@#
   0 +----------------------------------------------------------------------->Gi
     0                                                                   3.911
...
--------------------------------------------------------------------------------
  n        time(i)         total(B)   useful-heap(B) extra-heap(B)    stacks(B)
--------------------------------------------------------------------------------
 53  4,199,023,387    2,667,110,728    2,565,850,657   101,260,071            0
96.20% (2,565,850,657B) (heap allocation functions) malloc/new/new[], --alloc-fns, etc.
->92.58% (2,469,285,888B) 0x947720A: xmlHashCreate (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1)
| ->92.58% (2,469,285,888B) 0x94B006C: xmlXPathNewContext (in /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.1)
|   ->92.58% (2,469,285,888B) 0x55DBB6D: _CFXMLNodesForXPath (in /home/djones6/.swiftenv/versions/4.0-DEVELOPMENT-SNAPSHOT-2017-06-12-a/usr/lib/swift/linux/libFoundation.so)
|     ->92.58% (2,469,285,888B) 0x596713F: Foundation.XMLNode.nodes(forXPath: Swift.String) throws -> [Foundation.XMLNode] (in /home/djones6/.swiftenv/versions/4.0-DEVELOPMENT-SNAPSHOT-2017-06-12-a/usr/lib/swift/linux/libFoundation.so)
|       ->92.58% (2,469,273,600B) 0x401EFD: main (in /home/djones6/tests/xmlLeak_sr)
@swift-ci
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Comment by Matt Rajca (JIRA)

#1176

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Comment by Steven Van Impe (JIRA)

Thanks for fixing this. What release will this fix be available in?

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Comment by David Jones (JIRA)

The fix has been merged into the 4.0 branch: #1179

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
@shahmishal shahmishal transferred this issue from apple/swift May 5, 2022
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