[USRP-users] UHD and Thread Safety

Andy Walls andy at silverblocksystems.net
Thu Dec 11 15:27:25 EST 2014

FWIW, I use a custom GNURadio block for closed loop monitoring of GPSDO and USRP time between the host and the USRP.  Polling every two seconds, 25 msec after the PPS, I occasionally see UHD gripe about the GPRMC message not being available.  I never bothered to track down the cause.


On December 11, 2014 3:16:41 PM EST, Ben Hilburn via USRP-users <usrp-users at lists.ettus.com> wrote:
>Okay, we are debating the safety of polling for sensor data here within
>R&D team. At this point, we have flip-flopped several times.
>Balint will respond shortly with our final guidance =)
>On Thu, Dec 11, 2014 at 12:14 PM, Ben Hilburn <ben.hilburn at ettus.com>
>> Actually, what I just said is wrong, because calling those functions
>> result in packets being sent from the device.
>> So, no. Nothing is thread safe, and even polling for sensor data
>> cause issues.
>> Cheers,
>> Ben
>> On Thu, Dec 11, 2014 at 12:12 PM, Ben Hilburn <ben.hilburn at ettus.com>
>> wrote:
>>> Hi Nathan -
>>> Generally, any UHD function that doesn't involve streaming is *not
>>> So if you called "get_time_now" from two separate threads at the
>same time,
>>> that is *not* a thread-safe operation.
>>> If all you are doing is polling sensors from a thread that is
>>> from the thread in which you started streaming, you should be OK.
>But, it
>>> is not technically thread safe.
>>> Cheers,
>>> Ben
>>> On Tue, Dec 9, 2014 at 1:31 PM, Perelman, Nathan via USRP-users <
>>> usrp-users at lists.ettus.com> wrote:
>>>> I’ve been assuming that calls to UHD functions that don’t change
>>>> settings on the USRP are generally thread safe and can be called
>>>> another thread even while a capture is ongoing. Is this an accurate
>>>> assumption? The functions I’m calling are get_mboard_sensor() (for
>>>> information and ref_locked) and get_time_now(). Thanks.
>>>> -Nathan Perelman
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