hotfix/memfile-ack-logic-deadlock #1795
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… to "deadlock" in case of very long ack timeout setting
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…ptions from this process
| void CDataWriterSHM::RemoveSubscription(const std::string& host_name_, const int32_t process_id_, const std::string& topic_id_) | ||
| { | ||
| // we accept local disconnections only | ||
| if (host_name_ != m_attributes.host_name) return; |
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I am not sure that this is correct. If we communicate through docker images, we might have different host_name, but identical host_group.
Anyways, who applies the RemoveSubscription?
If you remove only subscriptions from IDs which have previously been subscribed, you don't need to do any checks here.
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Description
If the shm data transport layer acknowledgment feature is used and the ack time is set to a large value the publisher send may wait for a this long time on the ack event from the subscriber even the subscriber is no more existing (process is terminated for example). The SHM Datawriter Connect/Disconnect API is locked as long the Datawriter is waiting for the ack signal. That leads to a lock of the Registration layer finally.
Solution:
RemoveSubscriptiontoCDataWriterSHMto react on un-registrations from the registration layer in generalConnect/Disconnectfunctionality ofCSyncMemoryFilefromSyncContent()to be able to modify the map of the memfile connection events evenSyncContent()is waiting on a sync event.