Java synchronized method concurrent execution

I read this puzzle years ago (unfortunately I can't find the reference) but didn't appreciate it at the time. Java synchronized methods [1] can supposedly be invoked only by a single thread at a time. The essence of aforementioned puzzle was that, if the synchronized method obtains a lock on the object the method belongs … Continue reading Java synchronized method concurrent execution →

Debugging Spring REST bad request 400 codes

This happens way too often: you POST or PUT something to a Spring @RestController and Spring only tells you that there is a bad request, HTTP 400 code; no further explanations, no logs, no exceptions. Spring logs the error cause under the category "org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod" so you can enable logging for that in your log4j.properties: log4j.logger.org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod=DEBUG,stdout … Continue reading Debugging Spring REST bad request 400 codes →

Ansible local_action privilege de-escalation or: how to wait for a reboot

I increasingly use Ansible not only for glorious tasks like setting up my various VMs I use for prototyping but also for mundane things like resetting my personal laptop every time I get a new one or break it (dedicated readers of this blog will know me to do that a lot [2],[3],[4]). Most of … Continue reading Ansible local_action privilege de-escalation or: how to wait for a reboot →

End-to-end testing Java web applications with an embedded Tomcat

In this instalment on assembly testing [1] I'll talk about how automated system tests run over my Java web applications. The set-up is rather cheap, not very labour-intensive and can incrementally evolve from a simple assembly test (aka smoke test) to a full-fledged system test. Since this post is rather concrete naming tools and frameworks, … Continue reading End-to-end testing Java web applications with an embedded Tomcat →

SSLHandshakeException: unsupported certificate

When: loading client certificates from a custom keystore Reason: multiple certificates for the same domain but different purposes, e.g. one certificate handles email authentication, the other authenticates the user against a web server Solution: either fix the buggy code that selects the wrong certificate from the keystore or make sure only one certificate per domain … Continue reading SSLHandshakeException: unsupported certificate →