Ryan Herbert created PROTON-2396:
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Summary: Seed in uuid.cpp can lead to duplicates
Key: PROTON-2396
URL: https://issues.apache.org/jira/browse/PROTON-2396
Project: Qpid Proton
Issue Type: Bug
Components: cpp-binding
Environment: RHEL7 running in OpenStack
docker-ce 19.03.5
qpid-proton 0.28.0
qpid-cpp 1.37.0
Reporter: Ryan Herbert
The random number seed used in qpid-proton/cpp/src/uuid.cpp is based on the
current time and the PID of the running process. When starting multiple proton
instances simultaneously in Docker containers via automated deployment, there
is a high probability that multiple instances will get the same seed since the
PID within the Docker container is consistent and the same across multiple
copies of the same Docker container.
This results in duplicate link names when binding to exchanges. When this
happens, the queue gets bound to two different exchanges, and requests sent to
one exchange will get responses from both services.
To work around this error, we are specifying the link name via
sender_options/receiver_options every time we open a new sender/receiver, and
we also specify the container_id in connection_options. We are using
std::mt19937_64 seeded with
std::chrono::system_clock::now().time_since_epoch.count() to generate the
random part of our link names, which seems to have enough randomness that it
has eliminated the problem for us.
As pointed out in the Proton user forum, std::random_device is probably a
better choice for initializing the seed.
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