"HikariPool-1 - Connection is not available, request timed out after 30004ms." exception occurs only on the development server - spring-boot

Question

"Hikari Pool-1 - Connection is not available, request timed out after 30004ms." exception occurs only on the development server.
I spent a lot of time trying to find this problem, but I couldn't. For the first time in my life, I'm posting a question on stackoverflow.Please let me know if there is anything lacking in the question.
For your understanding, I have placed an example source code on GitHub.
I included the DDL Query used in the example below the resource folder and the log file (dev-log.out) on the actual development server.
I wrote down what I wanted to ask you at the bottom.
The requirements I am trying to implement are as follows.
Put the data from the source table into the target table.
If an exception occurs in the process of 1), the transaction is rolled back and the corresponding exception information is loaded on the log table.
To meet this requirement, I declared #Transactional to a service class (DemoService class in the example) that performs 1).
#RequiredArgsConstructor
#Service
public class DemoService {
private final DemoRepository repository;
#Transactional
#Logging
public void run() {
List<Integer> ids = repository.select(); //select from source table
for (Integer id : ids) {
repository.insert(id); //insert into target table
//An exception was made intentionally to roll back test
if (id == 1) {
throw new RuntimeException("exception~~");
}
}
}
}
And I wrote Aop using #Aspect (LoggingAspect in the example) to load exception information into the table. And I gave the REQUIRES_NEW option because the transaction loading exception information should be committed separately from the transaction used in 1).
#RequiredArgsConstructor
#Slf4j
#Component
#Aspect
public class LoggingAspect {
private final LoggingService loggingService;
#AfterThrowing(value = "#annotation(com.example.dbcpquestion.logging.Logging)", throwing = "ex")
public void doLog(JoinPoint joinPoint, Exception ex) throws Throwable {
log.error("-----------------------------------------");
int cnt = loggingService.logging();
log.error("cnt={}", cnt);
log.error("-----------------------------------------");
}
}
#RequiredArgsConstructor
#Service
public class LoggingService {
private final LoggingRepository repository;
#Transactional(propagation = Propagation.REQUIRES_NEW)
public int logging() {
return repository.save(); //insert exception info into log table
}
}
I know that if an exception occurs while performing 1) logic, at least two connections are required. (Transactions that work to move data from the Source table to the Target table that will eventually be rolled back, and transactions that load exception information into the log table)
The problem is!
The logic (1, 2) above works fine on the local PC, but when deployed to the development server, the exception "Hikari Pool-1 - Connection is not available, request timed out after 30004ms."
The strangest thing happens intermittently... (crazy)
Here's the Hikari setup log.
[2022-10-06 18:46:00.724] [DEBUG] [main] [HikariConfig ]- HikariPool-1 - configuration:
[2022-10-06 18:46:00.730] [DEBUG] [main] [HikariConfig ]- allowPoolSuspension................................false
[2022-10-06 18:46:00.730] [DEBUG] [main] [HikariConfig ]- autoCommit................................true
[2022-10-06 18:46:00.730] [DEBUG] [main] [HikariConfig ]- catalog................................none
[2022-10-06 18:46:00.730] [DEBUG] [main] [HikariConfig ]- connectionInitSql................................none
[2022-10-06 18:46:00.731] [DEBUG] [main] [HikariConfig ]- connectionTestQuery................................none
[2022-10-06 18:46:00.731] [DEBUG] [main] [HikariConfig ]- connectionTimeout................................30000
[2022-10-06 18:46:00.731] [DEBUG] [main] [HikariConfig ]- dataSource................................none
[2022-10-06 18:46:00.732] [DEBUG] [main] [HikariConfig ]- dataSourceClassName................................none
[2022-10-06 18:46:00.732] [DEBUG] [main] [HikariConfig ]- dataSourceJNDI................................none
[2022-10-06 18:46:00.734] [DEBUG] [main] [HikariConfig ]- dataSourceProperties................................{password=<masked>}
[2022-10-06 18:46:00.734] [DEBUG] [main] [HikariConfig ]- driverClassName................................"oracle.jdbc.OracleDriver"
[2022-10-06 18:46:00.734] [DEBUG] [main] [HikariConfig ]- exceptionOverrideClassName................................none
[2022-10-06 18:46:00.734] [DEBUG] [main] [HikariConfig ]- healthCheckProperties................................{}
[2022-10-06 18:46:00.734] [DEBUG] [main] [HikariConfig ]- healthCheckRegistry................................none
[2022-10-06 18:46:00.735] [DEBUG] [main] [HikariConfig ]- idleTimeout................................600000
[2022-10-06 18:46:00.735] [DEBUG] [main] [HikariConfig ]- initializationFailTimeout................................1
[2022-10-06 18:46:00.735] [DEBUG] [main] [HikariConfig ]- isolateInternalQueries................................false
[2022-10-06 18:46:00.735] [DEBUG] [main] [HikariConfig ]- jdbcUrl................................[Cleared for security reasons.]
[2022-10-06 18:46:00.736] [DEBUG] [main] [HikariConfig ]- keepaliveTime................................0
[2022-10-06 18:46:00.736] [DEBUG] [main] [HikariConfig ]- leakDetectionThreshold................................2000
[2022-10-06 18:46:00.736] [DEBUG] [main] [HikariConfig ]- maxLifetime................................1800000
[2022-10-06 18:46:00.736] [DEBUG] [main] [HikariConfig ]- maximumPoolSize................................3
[2022-10-06 18:46:00.737] [DEBUG] [main] [HikariConfig ]- metricRegistry................................none
[2022-10-06 18:46:00.737] [DEBUG] [main] [HikariConfig ]- metricsTrackerFactory................................none
[2022-10-06 18:46:00.737] [DEBUG] [main] [HikariConfig ]- minimumIdle................................3
[2022-10-06 18:46:00.737] [DEBUG] [main] [HikariConfig ]- password................................<masked>
[2022-10-06 18:46:00.737] [DEBUG] [main] [HikariConfig ]- poolName................................"HikariPool-1"
[2022-10-06 18:46:00.738] [DEBUG] [main] [HikariConfig ]- readOnly................................false
[2022-10-06 18:46:00.738] [DEBUG] [main] [HikariConfig ]- registerMbeans................................false
[2022-10-06 18:46:00.738] [DEBUG] [main] [HikariConfig ]- scheduledExecutor................................none
[2022-10-06 18:46:00.738] [DEBUG] [main] [HikariConfig ]- schema................................none
[2022-10-06 18:46:00.739] [DEBUG] [main] [HikariConfig ]- threadFactory................................internal
[2022-10-06 18:46:00.739] [DEBUG] [main] [HikariConfig ]- transactionIsolation................................default
[2022-10-06 18:46:00.739] [DEBUG] [main] [HikariConfig ]- username................................[Cleared for security reasons.]
[2022-10-06 18:46:00.739] [DEBUG] [main] [HikariConfig ]- validationTimeout................................5000
[2022-10-06 18:46:00.739] [INFO ] [main] [HikariDataSource ]- HikariPool-1 - Starting...
[2022-10-06 18:46:02.249] [DEBUG] [main] [HikariPool ]- HikariPool-1 - Added connection oracle.jdbc.driver.T4CConnection#1fc684e
[2022-10-06 18:46:02.252] [INFO ] [main] [HikariDataSource ]- HikariPool-1 - Start completed.
[2022-10-06 18:46:02.288] [INFO ] [main] [DemoService ]- [select]..................
[2022-10-06 18:46:02.361] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Pool stats (total=1, active=1, idle=0, waiting=0)
[2022-10-06 18:46:02.369] [DEBUG] [HikariPool-1 connection adder] [PoolBase ]- HikariPool-1 - Failed to create/setup connection: null
[2022-10-06 18:46:02.390] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
Yaml file settings.
Logging level has been set to DEBUG.
Hikari's maximum-pool-size is set to 3. As far as I know, I can set it to 2, but...I added one more connection
I also set leak-detection-threshold to look at connection leak.
As an example, url was specified as localhost, but the URL is actually specified as an IP address, not localhost. Both local profiles and dev profiles have the same DB connection information.
spring:
datasource:
username: dbcp
password: dbcp
driver-class-name: oracle.jdbc.OracleDriver
hikari:
maximum-pool-size: 3
leak-detection-threshold: 2000
logging:
pattern:
console: "[%d{yyyy-MM-dd HH:mm:ss.SSS}] [%-5level] [%thread] [%-25logger{0}]- %msg%n"
level:
'[com.zaxxer.hikari]': trace
'[com.zaxxer.hikari.HikariConfig]': debug
---
spring:
config:
activate:
on-profile: local
datasource:
url: jdbc:oracle:thin:#localhost:1521:orcl
#As an example, url was specified as localhost, but the URL is actually specified as an IP address, not localhost. Both local profiles and dev profiles have the same DB connection information.
---
spring:
config:
activate:
on-profile: dev
datasource:
url: jdbc:oracle:thin:#localhost:1521:orcl
The entire log.(Omit part of the log because of the number of characters.)
[2022-10-06 18:46:02.361] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Pool stats (total=1, active=1, idle=0, waiting=0)
[2022-10-06 18:46:02.369] [DEBUG] [HikariPool-1 connection adder] [PoolBase ]- HikariPool-1 - Failed to create/setup connection: null
[2022-10-06 18:46:02.390] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
at java.base/java.lang.String.getBytes(String.java:982)
at java.base/java.lang.ProcessEnvironment$Variable.valueOfQueryOnly(ProcessEnvironment.java:166)
at java.base/java.lang.ProcessEnvironment$Variable.valueOfQueryOnly(ProcessEnvironment.java:162)
at java.base/java.lang.ProcessEnvironment$StringEnvironment.get(ProcessEnvironment.java:239)
at java.base/java.lang.ProcessEnvironment$StringEnvironment.get(ProcessEnvironment.java:221)
at java.base/java.util.Collections$UnmodifiableMap.get(Collections.java:1454)
at java.base/java.lang.ProcessEnvironment.getenv(ProcessEnvironment.java:85)
at java.base/java.lang.System.getenv(System.java:1001)
at oracle.jdbc.driver.PhysicalConnection.lambda$getTnsAdminFromEnv$4(PhysicalConnection.java:10990)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at oracle.jdbc.driver.PhysicalConnection.getTnsAdminFromEnv(PhysicalConnection.java:10987)
at oracle.jdbc.driver.PhysicalConnection.readConnectionProperties(PhysicalConnection.java:1427)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:941)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:926)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:542)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:69)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:728)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:649)
at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138)
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364)
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206)
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:476)
at com.zaxxer.hikari.pool.HikariPool.access$100(HikariPool.java:71)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:726)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:712)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
[2022-10-06 18:46:02.660] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
at java.base/java.lang.String.getBytes(String.java:982)
at java.base/java.lang.ProcessEnvironment$Variable.valueOfQueryOnly(ProcessEnvironment.java:166)
at java.base/java.lang.ProcessEnvironment$Variable.valueOfQueryOnly(ProcessEnvironment.java:162)
at java.base/java.lang.ProcessEnvironment$StringEnvironment.get(ProcessEnvironment.java:239)
/////Omit part of the log because of the number of characters.
[2022-10-06 18:46:02.928] [ERROR] [main] [LoggingAspect ]- -----------------------------------------
[2022-10-06 18:46:03.055] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
/////Omit part of the log because of the number of characters.
[2022-10-06 18:46:03.624] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
/////Omit part of the log because of the number of characters.
[2022-10-06 18:46:04.278] [WARN ] [HikariPool-1 housekeeper] [ProxyLeakTask ]- Connection leak detection triggered for oracle.jdbc.driver.T4CConnection#1fc684e on thread main, stack trace follows
java.lang.Exception: Apparent connection leak detected
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:265)
/////Omit part of the log because of the number of characters.
[2022-10-06 18:46:04.475] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
/////Omit part of the log because of the number of characters.
[2022-10-06 18:46:05.745] [DEBUG] [HikariPool-1 connection adder] [HikariPool ]- HikariPool-1 - Cannot acquire connection from data source
java.lang.NullPointerException: null
at java.base/java.lang.StringCoding.encode(StringCoding.java:652)
[2022-10-06 18:46:32.371] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Pool stats (total=1, active=1, idle=0, waiting=1)
[2022-10-06 18:46:32.371] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Fill pool skipped, pool is at sufficient level.
[2022-10-06 18:46:32.931] [DEBUG] [main] [HikariPool ]- HikariPool-1 - Timeout failure stats (total=1, active=1, idle=0, waiting=0)
[2022-10-06 18:46:32.955] [INFO ] [main] [ProxyLeakTask ]- Previously reported leaked connection oracle.jdbc.driver.T4CConnection#1fc684e on thread main was returned to the pool (unleaked)
[2022-10-06 18:46:32.961] [INFO ] [main] [ConditionEvaluationReportLoggingListener]-
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
[2022-10-06 18:46:33.010] [ERROR] [main] [SpringApplication ]- Application run failed
java.lang.IllegalStateException: Failed to execute ApplicationRunner
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:776)
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:763)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
at com.springboot.example.ExampleApplication.main(ExampleApplication.java:19)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88)
Caused by: org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30004ms.
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:309)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.startTransaction(AbstractPlatformTransactionManager.java:400)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.handleExistingTransaction(AbstractPlatformTransactionManager.java:434)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:352)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:595)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:382)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708)
at com.springboot.example.logging.LoggingService$$EnhancerBySpringCGLIB$$f2e4eeed.logging(<generated>)
at com.springboot.example.logging.LoggingAspect.doLog(LoggingAspect.java:23)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:634)
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:617)
at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:68)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708)
at com.springboot.example.DemoService$$EnhancerBySpringCGLIB$$3b65fd43.run(<generated>)
at com.springboot.example.ExampleApplication.lambda$applicationRunner$0(ExampleApplication.java:27)
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:773)
... 13 common frames omitted
Caused by: java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30004ms.
at com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:696)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:197)
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162)
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:265)
... 45 common frames omitted
[2022-10-06 18:46:33.020] [INFO ] [main] [HikariDataSource ]- HikariPool-1 - Shutdown initiated...
[2022-10-06 18:46:33.020] [DEBUG] [main] [HikariPool ]- HikariPool-1 - Before shutdown stats (total=1, active=0, idle=1, waiting=0)
[2022-10-06 18:46:33.023] [DEBUG] [HikariPool-1 connection closer] [PoolBase ]- HikariPool-1 - Closing connection oracle.jdbc.driver.T4CConnection#1fc684e: (connection evicted)
[2022-10-06 18:46:40.826] [DEBUG] [main] [HikariPool ]- HikariPool-1 - After shutdown stats (total=0, active=0, idle=0, waiting=0)
[2022-10-06 18:46:40.826] [INFO ] [main] [HikariDataSource ]- HikariPool-1 - Shutdown completed.
What I checked to solve this problem is as follows.
I checked the settings of the Oracle DB server.
'IDLE_TIME' is set much longer than Hikari maxLifeTime.
'CONNECT_TIME' is unlimit.
We excluded the setting to load all spring bean into Lazy.
The actual project uses Mybatis, but if you look at what happens when you use JdbcTemplate, as in the example...I don't think Mybatis or Lazy loading is the cause.
The local DB and the DB used by the development server are all the same.
I confirmed that there were three sessions connected from Oracle when the problem did not occur and that there was one session connected when the exception occurred. From this, I expected that the connection itself would not be obtained.
What I'm curious about is as follows.
When logging level is set to DEBUG, the message 'Hikari Pool-1 - Canot acquisition connection from data source' appears frequently. Is it related to this part? (And what does this message mean?) Is the network unstable?)
If you look at the entire log,
[2022-10-06 18:46:32.371] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Pool stats (total=1, active=1, idle=0, waiting=1)
[2022-10-06 18:46:32.371] [DEBUG] [HikariPool-1 housekeeper] [HikariPool ]- HikariPool-1 - Fill pool skipped, pool is at sufficient level.
[2022-10-06 18:46:32.931] [DEBUG] [main] [HikariPool ]- HikariPool-1 - Timeout failure stats (total=1, active=1, idle=0, waiting=0)
~~~~
Caused by: org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30004ms.
This log remains. Can I say that it was 'waiting=1' and then changed to 'waiting=0' because a timeout exception occurred...?
Is it because you didn't get the connection?
Can't I run the application after the connection pool has three connections set to maximum-pool-size? As far as I know, Hikari's separate threads are out of control because they serve to get Connection.
I'd really appreciate your help.