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journald/read: avoid piling up open files

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If we take a long time to process log messages, and during that time
journal file rotation occurs, the journald client library will keep
those rotated files open until sd_journal_process() is called.

By periodically calling sd_journal_process() during the processing
loop we shrink the window of time a client instance has open file
descriptors for rotated (deleted) journal files.

This code is modelled after that of journalctl [1]; the above explanation
as well as the value of 1024 is taken from there.

[v2: fix CErr() argument]

[1] https://github.com/systemd/systemd/blob/dc16327c48d/src/journal/journalctl.c#L2676
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2019-03-10 03:39:33 +00:00
parent f091febc94
commit b73fb8fd5d
1 changed files with 11 additions and 0 deletions

11
daemon/logger/journald/read.go
View file

@ -113,6 +113,7 @@ import (
"github.com/coreos/go-systemd/journal"
"github.com/docker/docker/api/types/backend"
"github.com/docker/docker/daemon/logger"
"github.com/sirupsen/logrus"
)
func (s *journald) Close() error {
@ -205,6 +206,16 @@ drain:
}:
shown++
}
// Call sd_journal_process() periodically during the processing loop
// to close any opened file descriptors for rotated (deleted) journal files.
if shown%1024 == 0 {
if ret := C.sd_journal_process(j); ret < 0 {
// log a warning but ignore it for now
logrus.WithField("container", s.vars["CONTAINER_ID_FULL"]).
WithField("error", CErr(ret)).
Warn("journald: error processing journal")
}
}
}
// If we're at the end of the journal, we're done (for now).
if C.sd_journal_next(j) <= 0 {