WARN JdbcChannelMessageStore Message with id was not deleted - spring-integration

Question

I have a queue channel backed by a JdbcChannelMessageStore. I have two instances of this application and with high concurrency I have this warning:
2020-03-13 19:25:38,209 task-scheduler-5 WARN JdbcChannelMessageStore:652 - Message with id '06b73eab-727a-780f-d0fa-1b0e0dd1ea20' was not deleted.
Is there a way to remove them?
As far as my understanding, messages are being read twice, am I correct?
I am using SI 4.3.19.RELEASE. Here is my spring flow
<int:channel id="channel">
<int:queue message-store="messageStoreBean"/>
</int:channel>
<int:header-value-router input-channel="channel
header-name="name" >
<int:poller max-messages-per-poll="2" fixed-rate="500" >
<int:transactional />
</int:poller>
...
</int:header-value-router>
<bean id="storeQueryProviderBean" class="org.springframework.integration.jdbc.store.channel.PostgresChannelMessageStoreQueryProvider" />
<bean id="messageStoreBean" class="org.springframework.integration.jdbc.store.JdbcChannelMessageStore">
<property name="dataSource" ref="messageStoreDataSource" />
<property name="channelMessageStoreQueryProvider" ref="storeQueryProviderBean" />
<property name="region" value="region" />
</bean>

Answer 1

It looks like PostgreSQL doesn't guarantee exclusive reading with transactions and LIMIT 1 FOR UPDATE.
Anyway that WARN is just a note that some other process has removed the message. Nothing is duplicated if other process is similar to that poller:
public Message<?> pollMessageFromGroup(Object groupId) {
final String key = getKey(groupId);
final Message<?> polledMessage = this.doPollForMessage(key);
if (polledMessage != null) {
if (!this.doRemoveMessageFromGroup(groupId, polledMessage)) {
return null;
}
}
return polledMessage;
}
You see if message was not removed, we return null therefore nothing to poll at the moment.
You can turn off the warning level for the org.springframework.integration.jdbc.store.JdbcChannelMessageStore to avoid that message specifying a category level as ERROR in your logging config.