使用oss 存储checkpoint，做几次checkpoint就会出现下面报错，导致checkpoint失败
Caused by: org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.ClientException: Connection error due to: Trying to access closed classloader. Please check if you store classloaders directly or indirectly in static fields. If the stacktrace suggests that the leak occurs in a third party library and cannot be fixed immediately, you can disable this check with the configuration 'classloader.check-leaked-classloader'. [ErrorCode]: Unknown [RequestId]: Unknown at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.common.comm.ServiceClient.sendRequestImpl(ServiceClient.java:170) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.common.comm.ServiceClient.sendRequest(ServiceClient.java:70) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.send(OSSOperation.java:83) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.doOperation(OSSOperation.java:145) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.doOperation(OSSOperation.java:102) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSObjectOperation.writeObjectInternal(OSSObjectOperation.java:897) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSObjectOperation.putObject(OSSObjectOperation.java:129) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.OSSClient.putObject(OSSClient.java:471) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.OSSClient.putObject(OSSClient.java:455) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.aliyun.oss.AliyunOSSFileSystemStore.uploadObject(AliyunOSSFileSystemStore.java:414) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.aliyun.oss.AliyunOSSOutputStream.close(AliyunOSSOutputStream.java:87) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:101) ~[?:?] at org.apache.flink.fs.osshadoop.common.HadoopDataOutputStream.close(HadoopDataOutputStream.java:52) ~[?:?] at org.apache.flink.runtime.state.filesystem.FsCheckpointMetadataOutputStream.closeAndFinalizeCheckpoint(FsCheckpointMetadataOutputStream.java:131) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.state.filesystem.FsCheckpointMetadataOutputStream.closeAndFinalizeCheckpoint(FsCheckpointMetadataOutputStream.java:40) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.checkpoint.PendingCheckpoint.finalizeCheckpoint(PendingCheckpoint.java:323) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.completePendingCheckpoint(CheckpointCoordinator.java:1182) ~[flink-dist_2.11-1.13.6.jar:1.13.6] ... 10 more Caused by: java.lang.IllegalStateException: Trying to access closed classloader. Please check if you store classloaders directly or indirectly in static fields. If the stacktrace suggests that the leak occurs in a third party library and cannot be fixed immediately, you can disable this check with the configuration 'classloader.check-leaked-classloader'. at org.apache.flink.runtime.execution.librarycache.FlinkUserCodeClassLoaders$SafetyNetWrapperClassLoader.ensureInner(FlinkUserCodeClassLoaders.java:164) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.execution.librarycache.FlinkUserCodeClassLoaders$SafetyNetWrapperClassLoader.getResources(FlinkUserCodeClassLoaders.java:188) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.commons.logging.LogFactory$4.run(LogFactory.java:1307) ~[?:?] at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_241] at org.apache.commons.logging.LogFactory.getResources(LogFactory.java:1325) ~[?:?] at org.apache.commons.logging.LogFactory.getConfigurationFile(LogFactory.java:1403) ~[?:?] at org.apache.commons.logging.LogFactory.getFactory(LogFactory.java:455) ~[?:?] at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:657) ~[?:?] at org.apache.http.impl.conn.DefaultHttpResponseParser.<init>(DefaultHttpResponseParser.java:59) ~[?:?] at org.apache.http.impl.conn.DefaultHttpResponseParserFactory.create(DefaultHttpResponseParserFactory.java:76) ~[?:?] at org.apache.http.impl.DefaultBHttpClientConnection.<init>(DefaultBHttpClientConnection.java:99) ~[?:?] at org.apache.http.impl.conn.DefaultManagedHttpClientConnection.<init>(DefaultManagedHttpClientConnection.java:74) ~[?:?] at org.apache.http.impl.conn.LoggingManagedHttpClientConnection.<init>(LoggingManagedHttpClientConnection.java:66) ~[?:?] at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.create(ManagedHttpClientConnectionFactory.java:127) ~[?:?] at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.create(ManagedHttpClientConnectionFactory.java:57) ~[?:?] at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$InternalConnectionFactory.create(PoolingHttpClientConnectionManager.java:605) ~[?:?] at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$InternalConnectionFactory.create(PoolingHttpClientConnectionManager.java:576) ~[?:?] at org.apache.http.pool.AbstractConnPool.getPoolEntryBlocking(AbstractConnPool.java:360) ~[?:?] at org.apache.http.pool.AbstractConnPool.access$200(AbstractConnPool.java:67) ~[?:?] at org.apache.http.pool.AbstractConnPool$2.get(AbstractConnPool.java:243) ~[?:?] at org.apache.http.pool.AbstractConnPool$2.get(AbstractConnPool.java:191) ~[?:?] at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.leaseConnection(PoolingHttpClientConnectionManager.java:282) ~[?:?] at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$1.get(PoolingHttpClientConnectionManager.java:269) ~[?:?] at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:191) ~[?:?] at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185) ~[?:?] at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:111) ~[?:?] at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185) ~[?:?] at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.common.comm.DefaultServiceClient.sendRequestCore(DefaultServiceClient.java:124) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.common.comm.ServiceClient.sendRequestImpl(ServiceClient.java:133) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.common.comm.ServiceClient.sendRequest(ServiceClient.java:70) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.send(OSSOperation.java:83) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.doOperation(OSSOperation.java:145) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSOperation.doOperation(OSSOperation.java:102) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSObjectOperation.writeObjectInternal(OSSObjectOperation.java:897) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.internal.OSSObjectOperation.putObject(OSSObjectOperation.java:129) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.OSSClient.putObject(OSSClient.java:471) ~[?:?] at org.apache.flink.fs.osshadoop.shaded.com.aliyun.oss.OSSClient.putObject(OSSClient.java:455) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.aliyun.oss.AliyunOSSFileSystemStore.uploadObject(AliyunOSSFileSystemStore.java:414) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.aliyun.oss.AliyunOSSOutputStream.close(AliyunOSSOutputStream.java:87) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.FSDataOutputStream$PositionCache.close(FSDataOutputStream.java:72) ~[?:?] at org.apache.flink.fs.shaded.hadoop3.org.apache.hadoop.fs.FSDataOutputStream.close(FSDataOutputStream.java:101) ~[?:?] at org.apache.flink.fs.osshadoop.common.HadoopDataOutputStream.close(HadoopDataOutputStream.java:52) ~[?:?] at org.apache.flink.runtime.state.filesystem.FsCheckpointMetadataOutputStream.closeAndFinalizeCheckpoint(FsCheckpointMetadataOutputStream.java:131) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.state.filesystem.FsCheckpointMetadataOutputStream.closeAndFinalizeCheckpoint(FsCheckpointMetadataOutputStream.java:40) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.checkpoint.PendingCheckpoint.finalizeCheckpoint(PendingCheckpoint.java:323) ~[flink-dist_2.11-1.13.6.jar:1.13.6] at org.apache.flink.runtime.checkpoint.CheckpointCoordinator.completePendingCheckpoint(CheckpointCoordinator.java:1182) ~[flink-dist_2.11-1.13.6.jar:1.13.6] ... 10 more
