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multiple Threads read to the same table in database by using the same connection in java?

I have defined three transaction in which select operations and SELECT operations are happening on the different parameter passed . I try to invoke this method concurrently . I am get an error:
o.h.engine.jdbc.spi.SqlExceptionHelper : SQL Error: 0, SQLState: null
Aug 25, 2020 # 12:16:39.000 2020-08-25 06:46:39.388 ERROR 1 --- [o-9003-exec-630] o.h.engine.jdbc.spi.SqlExceptionHelper : Hikari - Connection is not available, request timed out after 60000ms.
And sometimes
org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
I am new to java. Please guide me to solve this issue. Do I need to write multithreading to access number of resources or configuration issue?
hikari:
poolName: Hikari
autoCommit: false
minimumIdle: 5
connectionTimeout: 60000
maximumPoolSize: 80
idleTimeout: 60000
maxLifetime: 240000
leakDetectionThreshold: 300000

Multiple Threads read to the same table in database by using the same connection in java?
This is generally speaking not going to work. The JDBC API types Connection, Statement, ResultSet and so on are not generally thread-safe1. You should not try to use on instance in multiple threads.
If you want to avoid having multiple connections open the normal approach is to use a JDBC connection pool to manage the connections. When a thread needs to talk to the database, it gets a connection from the pool. When it has finished talking to the database, it releases it back to the pool.
In the PostgreSQL / Hikari case:
For PostgreSQL - "Using the driver in a multi-threaded or a servlet environment"
For Hikari - the getConnection() call is thread-safe, but I couldn't find anything that explicitly talked about the thread-safety of the connection object when shared by multiple threads.
1 - I have seen it stated that a spec compliant JDBC driver should be thread-safe, but I could not see where the JDBC spec actually requires this to be so. But even assuming that it does say that somewhere, the threads sharing a connection would need to coordinate very carefully to avoid things like one thread causing another thread's resultset to "spontaneously" close.

Connection to Postgres database lost

On a performance server - with rather a big load, i have a weird behavior.
From one moment in time all the connection the database start to say "connection has been closed".
The only hint so far is this IOException :
Caused by: org.postgresql.util.PSQLException: An I/O error occurred while sending to the backend.
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:314)
at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:430)
at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:356)
at org.postgresql.jdbc.PgPreparedStatement.executeWithFlags(PgPreparedStatement.java:168)
at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:116)
at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:342)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1812)
at org.hibernate.loader.Loader.doQuery(Loader.java:697)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2232)
... 73 more
Caused by: java.io.IOException: Tried to send an out-of-range integer as a 2-byte value: 33001
at org.postgresql.core.PGStream.sendInteger2(PGStream.java:211)
at org.postgresql.core.v3.QueryExecutorImpl.sendParse(QueryExecutorImpl.java:1409)
at org.postgresql.core.v3.QueryExecutorImpl.sendOneQuery(QueryExecutorImpl.java:1729)
at org.postgresql.core.v3.QueryExecutorImpl.sendQuery(QueryExecutorImpl.java:1294)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:280)
... 83 more
However i can't really link it to some business scenario for the moment.
Any ideas ?

It's a PostgreSQL driver limitation, the maximum number of parameters for a query is 32768.
You have a query that exceeds that limit - and by doing so the driver has an erratic behavior of closing connections. I encountered that on a JBoss server using Hibernate with PostgreSQL and the connection closing led to a pretty messed up state of the connection pool.
This parameter is described here, in the Parse section:
"Int16 - The number of parameter data types specified".
The solution is to split that long query into smaller ones with a known number of parameters.

Record inserted but still not found

I was currently using java spring jdbctemplate to insert and select record. However, Now the system have go for production, some issue has happen. This system will prevent record duplicate by select the record by certain key to check is it already exist. However, I notice the 1st transaction after inserted into database, then the 2nd transaction come in, jdbc template select still show that record was not found? I notice this will happen if the 2 transaction was submitted within a milliseconds different...
The record time was
e.g.
1st Record insert - 15/6/17 12:22:39,986 - insert success
2nd record select - 15/6/17 12:22:44,680 - search record show not found?
Sample insert log
15/6/17 12:22:39,937 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:869) Executing prepared SQL update
15/6/17 12:22:39,938 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:616) Executing prepared SQL statement [INSERT INTO ...;]
15/6/17 12:22:39,950 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:879) SQL update affected 1 rows
15/6/17 12:22:39,951 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:869) Executing prepared SQL update
15/6/17 12:22:39,952 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:616) Executing prepared SQL statement [INSERT INTO ...;]
15/6/17 12:22:39,965 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.core.JdbcTemplate:879) SQL update affected 1 row
15/6/17 12:22:39,970 DEBUG [30:http-nio-8080-exec-2] (org.springframework.jdbc.datasource.DataSourceUtils:327) Returning JDBC Connection to DataSource
Sample select log
15/6/17 12:22:44,680 DEBUG [29:http-nio-8080-exec-1] (org.springframework.jdbc.core.JdbcTemplate:682) Executing prepared SQL query
15/6/17 12:22:44,680 DEBUG [29:http-nio-8080-exec-1] (org.springframework.jdbc.core.JdbcTemplate:616) Executing prepared SQL statement [SELECT * FROM ...]
Please note that this system was set in 2 different server by using load balancing. They both point to the same database. The insert was completed on server 1 because it already return the connection to the jdbc connection pool. A new transaction come in the server 2, select but no record found?
I wonder why it still cannot found event after insert was finish? Is it because of the time delay?

This question had been resolved. It was due to the server time not consistent. Thanks
RealSkeptic

org.springframework.jdbc.UncategorizedSQLException:PreparedStatementCallback; nested exception is com.ibm.db2.jcc.am.SqlException:

I get a
org.springframework.jdbc.UncategorizedSQLException: PreparedStatementCallback; uncategorized SQLException.
SQL state [51002]; error code [-805]; DB2 SQL Error: SQLCODE=-805, SQLSTATE=51002, SQLERRMC=NULLID.SYSLH203 0X5359534C564C3031, DRIVER=3.65.102; nested exception is com.ibm.db2.jcc.am.SqlException: DB2 SQL Error: SQLCODE=-805, SQLSTATE=51002, SQLERRMC=NULLID.SYSLH203 0X5359534C564C3031, DRIVER=3.65.102
for the following sql:
SELECT REF_TBL_ENTY_KEY, LTRIM(RTRIM(REF_TBL_ID)) AS REF_TBL_ID, LTRIM(RTRIM(COMP_ID1)) AS COMP_ID1, LTRIM(RTRIM(LOW_VAL1)) AS LOW_VAL1, LTRIM(RTRIM(HI_VAL1)) AS HI_VAL1, LTRIM(RTRIM(COMP_ID2)) AS COMP_ID2, LTRIM(RTRIM(LOW_VAL2)) AS LOW_VAL2, LTRIM(RTRIM(HI_VAL2)) AS HI_VAL2, LTRIM(RTRIM(COMP_ID3)) AS COMP_ID3, LTRIM(RTRIM(LOW_VAL3)) AS LOW_VAL3, LTRIM(RTRIM(HI_VAL3)) AS HI_VAL3, LTRIM(RTRIM(COMP_ID4)) AS COMP_ID4, LTRIM(RTRIM(LOW_VAL4)) AS LOW_VAL4, LTRIM(RTRIM(HI_VAL4)) AS HI_VAL4, LTRIM(RTRIM(COMP_ID5)) AS COMP_ID5, LTRIM(RTRIM(LOW_VAL5)) AS LOW_VAL5, LTRIM(RTRIM(HI_VAL5)) AS HI_VAL5, LTRIM(RTRIM(COMP_ID6)) AS COMP_ID6, LTRIM(RTRIM(LOW_VAL6)) AS LOW_VAL6, LTRIM(RTRIM(HI_VAL6)) AS HI_VAL6 FROM TBL_CODE WHERE DOM_NBR = ? AND REF_TBL_ID = ? AND EFF_DT <= ? AND END_DT >= ? AND LOW_VAL1 <= 'ABX' AND HI_VAL1 >= 'ABX' ORDER BY REF_TBL_ID, LOW_VAL1, HI_VAL1, LOW_VAL2, HI_VAL2, LOW_VAL3, HI_VAL3, LOW_VAL4, HI_VAL4, LOW_VAL5, HI_VAL5, LOW_VAL6, HI_VAL6, EFF_DT
I am using this sql in jdbcTemplate queryForList and am passing the required number of parameters. This error doesn't happen at all times.
This sql is being run as part of a long running batch job processing application. The application is single threaded. The application code DOES NOT open or close any connections explicitly.
I am using commons Dbcp(version 1.4) for connection pooling and spring JDBC(version 3.2.8) for data access. I have tried running it with BasicDataSource maxActive = 50 and maxActive=8(default for BasicDataSource) and I receive error in both cases.
In researching this issue I came accross this link from IBM website - http://www-01.ibm.com/support/docview.wss?rs=71&uid=swg21208123
The previous version of the application which used an in-house connection pooling framework and managed its own data access did not throw this exception. I want to make sure that the application code is fine before I request the DBA to create more packages on the server.
Any help will be greatly appreciated.

Table doesn't exist when deployed in server hibernate

When i deploy the web app on test server (it works fine on localhost ), this BLO_BlOCKED_MOBILES table at the given line of code.
Query query = this.getSession().createSQLQuery(
strQuery.append(" INSERT INTO BLO_BlOCKED_MOBILES (BLO_CUSTOMER_ID_FK,BLO_MOBILE,BLO_NEWMOBILE,BLO_PASSPORT,BLO_STATUS,BLOCKED_BY,BLOCKED_AT ) "
+"VALUES( "+customer.getId() +", '"+ oldMobile +"','"+newMobile+"','"+customer.getPassportNo()+"','Y','user',CURRENT_TIMESTAMP)" ).toString());
mtmrsLogger.info(query.toString());
int affectedRows = query.executeUpdate();
The db is in mysql and app uses hibernate,struts 1 and spring. I created this new table ,
added this on hibernate.cfg.xml
< mapping class="com.mtmrs.model.branch.BlockedMobile"/>
and created the model file BlockedMobile.java
and when it is used, the below error comes.
WARN org.hibernate.util.JDBCExceptionReporter - SQL Error: 1146, SQLState: 42S02
ERROR org.hibernate.util.JDBCExceptionReporter - Table 'merchantrade.blo_blocked_mobiles' doesn't exist
Please let me know if the information is insufficient. I don't see what's wrong.

Peraphs the two DB (on your localhost server and on test server) are different. So the test server has not got your table.

According to the error message, either the table blo_blocked_mobiles or the scheme merchantrade does not exist on the MySQL database on the test server.