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I was recently trying to add a package level suppression in both checkstyle / spotbugs and found it to be having wierd syntax. For checkstyle, First add a module in your checkstyle configuration file <module name="SuppressionFilter"> <property name="file" value="./suppressions.xml"/> </module> And then in the suppressions.xml , specify the package as follows: <?xml version="1.0"?> <!DOCTYPE suppressions PUBLIC "-//Puppy Crawl//DTD Suppressions 1.1//EN" "http://www.puppycrawl.com/dtds/suppressions_1_1.dtd"> <suppressions> <suppress files="[\\/]com[\\/]domain[\\/]package" checks="."/> </suppressions> For, Spotbugs, you specify the package level suppression in...

Recently, I was facing an issue in production where our backend service used to get stuck while making a HTTP client request through Apache HTTP After some debugging, I got this stack trace from the logs org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.leaseConnection(PoolingHttpClientConnectionManager.java:316) at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$1.get(PoolingHttpClientConnectionManager.java:282) at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:190) at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:186) at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89) at org.apache.http.impl.execchain.ServiceUnavailableRetryExec.execute(ServiceUnavailableRetryExec.java:85) at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110) 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.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) The pecuilar thing was that it was happening for only...

Recently, our ELK infrastructure went down which aggregates log from our multiple servers. I wanted to investigate a production issue which involved looking up logs of multiple servers simultaneously. I tried different methods such as tmux, multitail and ssh command such as ssh HOST_1 "tail -f /path/to/file" | tee -a /path/to/merged/contents ssh HOST_2 "tail -f /path/to/file" | tee -a /path/to/merged/contents tail -f /path/to/merged/contents All these are nice solutions, but none of them is elegant. It...

If any host is using self-signed certificate, then a typical HTTPS request to that host will fail in the Java code with the following exception: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target A very NOT recommended solution to this problem is to bypass the certificate check import java.security.cert.CertificateException; import java.security.cert.X509Certificate; import javax.net.ssl.X509TrustManager; public class TrustAnyTrustManager implements X509TrustManager { public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException...

Recently, I faced a production issue where some of our requests were failing with the following exception org.apache.coyote.http11.Http11Processor.service Error parsing HTTP request header Note: further occurrences of HTTP header parsing errors will be logged at DEBUG level. java.lang.IllegalArgumentException: Request header is too large at org.apache.coyote.http11.Http11InputBuffer.parseHeaders(Http11InputBuffer.java:583) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:703) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745) Interestingly, the occurence of these errors in the logs were very few...

Must have Java code analysis Tools - Part 1 Must have Java code analysis Tools - Part 2 In the last post, we looked at Spotbugs, which focuses on the code linting at the bytecode level. In this post, we will look at PMD, which agains works at the source level to find out possible bugs in your java code. The list of entire checks which PMD finds can be found here There is also...

Recently, I had a requirement to incrementally increase the traffic to a newer version of service we were deploying in production. We didn’t wanted to go with random percentage approach. This is because our users are mobile app users and we didn’t want the users to hit the older version and newer verison of service randomly. That is, we wanted to consistently map the user to either be routed to an older version of newer...

Must have Java code analysis Tools - Part 1 Must have Java code analysis Tools - Part 3 In the last post, we looked at checkstyle, which focuses on the code linting at the source level. In this post, we will look at SpotBugs, which is a successor of FindBugs. SpotBugs works at the bytecode level instead of the source level. Hence it is able, to find out possible bugs in your java code. The...

Must have Java code analysis Tools - Part 2 Must have Java code analysis Tools - Part 3 When you are working in a big team ( > 5 engineers), It is very important to have consistent code styling, development environment and code review process. As a reviewer, its very difficult I see different class naming conventions everytime, unused variables or imports etc. Hence, its very important that a team shares same coding styles and...

Recently, I tried to try out the Splunk for log aggregation instead of ELK stack. I wanted to see what are the advantages of it over ELK. Well, that’s reserved for another post. However, I faced an issue as soon as I start the splunk container. homePath='/opt/splunk/var/lib/splunk/audit/db' of index=_audit on unusable filesystem. Validating databases (splunkd validatedb) failed with code '1' The problem is that splunk relies on the filesystem with the locking mechanism while the...