Grails / HIbernate Postgresql cannot query previously created object - postgresql

Question

we are using Grails 4 with Hibernate 5 and Postgresql and I ran into a strange problem which I don't know how to troubleshoot.
I have created a test which creates a Family (a large object graph having around 20 INSERT and UPDATE queries) and then it tries to retrieve it using its id.
So there is a FamilyController extending grails.rest.RestfulControllerhaving static responseFormats = ['json'] and the following methods:
#Override
protected Family createResource() {
def instance = new NewFamilyCommand()
bindData(instance, getObjectToBind())
instance.validate()
//Check for binding errors
if(instance.hasErrors()) {
throw new ValidationException('Unable to bind new family', instance.errors)
}
//Send the command to the service, which will return us an actual Family domain object
return familyService.addFamilyToUser(instance)
}
and
#Override
protected Family queryForResource(Serializable id) {
def family = familyService.safeGetFamily(Long.parseLong(id))
...
return family
}
Running this in a loop using a Cypress test, and it works fine most of the time.
Problem is that from time to time (seems to be a multiple of 50 which coincidentally is the number of maxConnections configured in Tomcat) querying the Family by the returned id does not find it.
Here is the Tomcat configuration for the datasource (default recommended by Grails):
dataSource:
pooled: true
jmxExport: true
driverClassName: org.postgresql.Driver
dialect: "net.kaleidos.hibernate.PostgresqlExtensionsDialect"
username: "test"
password: "test"
properties:
initialSize: 2
maxActive: 50
minIdle: 2
maxIdle: 2
maxWait: 10000
maxAge: 10 * 60000
timeBetweenEvictionRunsMillis: 5000
minEvictableIdleTimeMillis: 60000
validationQuery: "SELECT 1"
validationQueryTimeout: 3
validationInterval: 15000
testOnBorrow: true
testWhileIdle: true
testOnReturn: false
jdbcInterceptors: "ConnectionState;StatementCache(max=200)"
defaultTransactionIsolation: 2 # TRANSACTION_READ_COMMITTED
removeAbandoned: true
removeAbandonedTimeout: 300
Postgresql runs in a docker container with 2 PIDS for this database, let's say 73 and 74.
I looked in the Postgresql logs and I noticed a difference between a successful test and a failed one.
In a successful scenario, both the Family creation and the Family retrieval run in the same PID.
In a failed scenario, the Family creation is performed by pid 74 and Family retrieval is performed by PID 73.
What is more curious is that PID 73 is idle most of the time, it runs it's first query around the creation of Family 50 (presumably when the connections are started to being reused) and then at Family 101 is getting used in the Family retrieval query, whose transaction begins before PID 74 Family creation transaction commits (at least that is shown in Postgres logs but maybe the logs are not printed chronologically).
Checking the database right after the test fails, I see the Family saved in the database and also the tests pass if I add a little wait time before querying for the result.
I am wondering how could that be, I assume that Postgresl return the ID only after the transaction is being committed, and then why would the other PID not see it?
Any help in troubleshooting this would be greatly appreciated.
UPDATE: seems to be related to Hibernate.FLUSH_MODE. If I set sessionFactory.currentSession.setFlushMode(FlushMode.MANUAL) in familyService.addFamilyToUser(instance) the problem goes away and the statements are properly ordered. It seems that Hibernate flushes the session too early returning the family id even if Postgres does not commit all the insert/update statements.

Answer 1

Looks like it was our fault, we messed around with the DirtyCheckable#hasChanged implementation and the code generated a lot of UPDATE statements after the initial insert and this caused the session to be flushed several times and the underlying Posgresql transactions were out of sync with the Hibernate transactions