Details
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Bug
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Resolution: Fixed
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P3: Somewhat important
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5.15, 6.3.1, 6.4.1
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None
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Linux/X11
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21
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83f079619 (dev), 6e269fe18 (6.7)
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Foundation Sprint 100
Description
Updating a QJsonObject with a string value causes increasing memory use, the following program exhibits the problem:
#include <QDebug> #include <QJsonObject> #include <QString> int main(int argc, char **argv) { QJsonObject container; while (true) { container.insert("key", "value"); qDebug() << container.size(); } return 0; }
Tested on default packages on Debian and Fedora36 for 5.15 as well as 6.3 on Debian.
5.12 does not exhibit the same problem, but as far as I can tell it doesn't use QCborContainerPrivate as the internal representation.
The problem is that the QByteArray in container.o.d.data keeps growing; after the first loop iteration it is :
data = "\003\000\000\000key\000\005\000\000\000value" = {
[0] = 3 '\003',
[1] = 0 '\000',
[2] = 0 '\000',
[3] = 0 '\000',
[4] = 107 'k',
[5] = 101 'e',
[6] = 121 'y',
[7] = 0 '\000',
[8] = 5 '\005',
[9] = 0 '\000',
[10] = 0 '\000',
[11] = 0 '\000',
[12] = 118 'v',
[13] = 97 'a',
[14] = 108 'l',
[15] = 117 'u',
[16] = 101 'e'
}
after the second:
data = "\003\000\000\000key\000\005\000\000\000value\000\000\000\005\000\000\000value" = {
[0] = 3 '\003',
[1] = 0 '\000',
[2] = 0 '\000',
[3] = 0 '\000',
[4] = 107 'k',
[5] = 101 'e',
[6] = 121 'y',
[7] = 0 '\000',
[8] = 5 '\005',
[9] = 0 '\000',
[10] = 0 '\000',
[11] = 0 '\000',
[12] = 118 'v',
[13] = 97 'a',
[14] = 108 'l',
[15] = 117 'u',
[16] = 101 'e',
[17] = 0 '\000',
[18] = 0 '\000',
[19] = 0 '\000',
[20] = 5 '\005',
[21] = 0 '\000',
[22] = 0 '\000',
[23] = 0 '\000',
[24] = 118 'v',
[25] = 97 'a',
[26] = 108 'l',
[27] = 117 'u',
[28] = 101 'e'
},
Presumably there's a bug in how strings are (re)allocated in QJsonObjects. There doesn't seem to be a problem with int-types. At least I haven't seen one.
Attachments
| For Gerrit Dashboard: QTBUG-109073 | ||||||
|---|---|---|---|---|---|---|
| # | Subject | Branch | Project | Status | CR | V |
| 536666,4 | Implement QCborContainerPrivate::compact() | dev | qt/qtbase | Status: MERGED | +2 | 0 |
| 537336,2 | Implement QCborContainerPrivate::compact() | 6.7 | qt/qtbase | Status: MERGED | +2 | 0 |