调用 DynamoDBMapper 的加载时有时会出现此错误：
java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:171)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
at java.io.BufferedInputStream.read1(BufferedInputStream.java:286)
at java.io.BufferedInputStream.read(BufferedInputStream.java:345)
at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:735)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1593)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1498)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
at com.amazonaws.internal.EC2ResourceFetcher.doReadResource(EC2ResourceFetcher.java:82)
at com.amazonaws.internal.InstanceMetadataServiceResourceFetcher.getToken(InstanceMetadataServiceResourceFetcher.java:91)
at com.amazonaws.internal.InstanceMetadataServiceResourceFetcher.readResource(InstanceMetadataServiceResourceFetcher.java:69)
at com.amazonaws.internal.EC2ResourceFetcher.readResource(EC2ResourceFetcher.java:66)
at com.amazonaws.auth.InstanceMetadataServiceCredentialsFetcher.getCredentialsEndpoint(InstanceMetadataServiceCredentialsFetcher.java:58)
at com.amazonaws.auth.InstanceMetadataServiceCredentialsFetcher.getCredentialsResponse(InstanceMetadataServiceCredentialsFetcher.java:46)
at com.amazonaws.auth.BaseCredentialsFetcher.fetchCredentials(BaseCredentialsFetcher.java:112)
at com.amazonaws.auth.BaseCredentialsFetcher.getCredentials(BaseCredentialsFetcher.java:68)
at com.amazonaws.auth.InstanceProfileCredentialsProvider.getCredentials(InstanceProfileCredentialsProvider.java:166)
at com.amazonaws.auth.EC2ContainerCredentialsProviderWrapper.getCredentials(EC2ContainerCredentialsProviderWrapper.java:75)
at com.amazonaws.auth.AWSCredentialsProviderChain.getCredentials(AWSCredentialsProviderChain.java:117)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.getCredentialsFromContext(AmazonHttpClient.java:1251)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.runBeforeRequestHandlers(AmazonHttpClient.java:827)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.doExecute(AmazonHttpClient.java:777)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.executeWithTimer(AmazonHttpClient.java:764)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.execute(AmazonHttpClient.java:738)
at com.amazonaws.http.AmazonHttpClient$RequestExecutor.access$500(AmazonHttpClient.java:698)
at com.amazonaws.http.AmazonHttpClient$RequestExecutionBuilderImpl.execute(AmazonHttpClient.java:680)
at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:544)
at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:524)
at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.doInvoke(AmazonDynamoDBClient.java:5110)
at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.invoke(AmazonDynamoDBClient.java:5077)
at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.executeGetItem(AmazonDynamoDBClient.java:2197)
at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.getItem(AmazonDynamoDBClient.java:2163)
at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:431)
at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.load(DynamoDBMapper.java:448)
at com.amazonaws.services.dynamodbv2.datamodeling.AbstractDynamoDBMapper.load(AbstractDynamoDBMapper.java:80)
我有 2 次 PUT /latest/api/token 超时，然后我得到响应。我不确定到底出了什么问题或为什么有时会出现这种行为，但这会导致我的应用程序出现延迟。
我需要修改设置中的某些内容吗？它与 DynamoMapper 有关吗？我应该使用低级 Dynamo API 吗？
