journal: normalize priority of logging sources

The stream event source has a priority of SD_EVENT_PRIORITY_NORMAL+5,
and stdout source +10, but the native and syslog event sources are left
at the default of 0.

As a result, any heavy native or syslog logger can cause starvation of
the other loggers.  This is trivially demonstrated by running:

 dd if=/dev/urandom bs=8k | od | systemd-cat & # native spammer
 systemd-run echo hello & # stream logger
 journalctl --follow --output=verbose --no-pager --identifier=echo &

... and wait, and wait, the "hello" never comes.

Now kill %1, "hello" arrives finally.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/journal/journald-stream.c b/src/journal/journald-stream.c
index 131fcdac42..90884b6929 100644
--- a/src/journal/journald-stream.c
+++ b/src/journal/journald-stream.c
@@ -733,7 +733,7 @@ int server_open_stdout_socket(Server *s) {
         if (r < 0)
                 return log_error_errno(r, "Failed to add stdout server fd to event source: %m");
 
-        r = sd_event_source_set_priority(s->stdout_event_source, SD_EVENT_PRIORITY_NORMAL+10);
+        r = sd_event_source_set_priority(s->stdout_event_source, SD_EVENT_PRIORITY_NORMAL+5);
         if (r < 0)
                 return log_error_errno(r, "Failed to adjust priority of stdout server event source: %m");