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Hello folks, we’re facing the following issue: An application does not receive DBUS signals via the DBUS file descriptor while waiting for a dbus-method response.
The basic setup: Two applications are communicating via DBUS, using a
select() loop waiting for events on the dbus-fd.
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Triggered by a timer event, Application A calls the dbus-method “transmit” of
application B.
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During processing of the “transmit”-method,
application B broadcasts a dbus-signal on which
application A is matched on.
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Afterwards,
application B sleeps for 5ms and then finishes its “transmit”-method by sending a response message towards
application A.
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The dbus-fd of
Application A does not trigger the select() afterwards (same for
epoll() if implemented so).
o
… when triggering
sd_bus_process() manually, the signal is being receved in
application A, meaning that the signal was in fact received and queued, but the event was not signalled.
o
… other processes, not being “blocked” by waiting for a response-message, do also receive the signal. We saw this behavior on multiple platforms, e.g. Linux kubuntu 4.4.0-137-generic with 229-4ubuntu21.1 and Debian Buster 4.18.0-2-am64 with systemd 239-10. Attached you can find a simple example, including application
A / B, a makefile and the correlating *.conf-files. Thanks in advance and
best regards, Jan Mueller |
<<attachment: mbsp_files.zip>>
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