Unreleased space after deleting files

[Niarolf]

Description

This issue follow the #37
When we have not enought space in the apache temp filesystem, the temporary files are now deleted in the 1.7.0 version but some space are unrealesed by the qgis_maps process.

Context

Qgis server is using with apache2 and fcgi.
When we call the plugin for a large file, send with a SHP outputFormat for example, the plugin create a gml file, then he converts this one in shp and finally in a zip file.
All theses files are deleted when no error and the final file is send, and when an error is occuring, the plugin stop, send a corrupt file and delete the temporary files but the space is not integrally unrealesed, qgis_maps process keep some space with the deleted files.
We must restart apache to unrealsed the space.

An extract of the lsof command :

COMMAND PID TID TASKCMD USER FD TYPE DEVICE SIZE/OFF NODE NAME
qgis_maps 61436 www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61436 61440 qgis_maps www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61436 61441 QXcbEvent www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61436 61442 Qt\x20bea www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61436 61443 QDBusConn www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61436 61444 QCA::KeyS www-data 20r REG 254,7 681464714 29 /tmp/QGIS_WfsOutputExtension/gml_features_1649074437.4294026.gml (deleted)
qgis_maps 61468 www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)
qgis_maps 61468 61472 qgis_maps www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)
qgis_maps 61468 61473 QXcbEvent www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)
qgis_maps 61468 61474 Qt\x20bea www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)
qgis_maps 61468 61475 QDBusConn www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)
qgis_maps 61468 61476 QCA::KeyS www-data 20r REG 254,7 681464714 37 /tmp/QGIS_WfsOutputExtension/gml_features_1649074453.1260824.gml (deleted)

• QGIS Server FULL version (with 3 numbers) :
  Qgis Server 3.16.15

• OS on the server :
  Debian 10.8

[Gustry]

We are aware but a lot of limitations of this plugin (first getting GML, writing to disk, transforming again the GML etc). We are thinking about a better process with WPS for later.

For your files, we don't have any issue so far for us. Not sure if it's related to Apache, we don't use it.