A particular USB harddrive won't show up in the device list under Ubuntu 18.04 when connected to a USB 3.0 port of the HP proliant microsever gen8 though it will show up when connected to a USB 2.0 port. The symptoms are that the drive won't list with fdisk -l nor how up under /dev/sdX. … Continue reading USB harddrive not showing on USB 3.0 port
Tag: debugging
Constant disk access with ext4 caused by kmmp
I don't know how I never noticed this, but the mechanical hard disks in the perfect NAS emit a clicking noise at regular intervals that never stops. The NAS runs Ubuntu 18.04 server, an md software RAID 6 with dmcrypt on top, formatted with ext4. Disk I/O is way too low to show anything useful … Continue reading Constant disk access with ext4 caused by kmmp
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
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
Heisenbugs with angular.js and Internet Explorer 9 or: missing console.log
I'm developing a proof of concept web application based on angular.js for corporate users, which - as so often in my career - means that they are using Internet Explorer. Several users complained about sporadic failures which were really hard to pin down, but during debugging sessions boiled down to a simple observation: the errors … Continue reading Heisenbugs with angular.js and Internet Explorer 9 or: missing console.log
AngularJS, Internet Explorer 9 and watch error
While working on an enterprise project (of course...) I run into an error with Angular (1.3.13), Internet Explorer 9 and $watch-ing a scope when programming a directive: TypeError: Object doesn't support property or method 'watch' I'll never find out what the reason is. The collective wisdom of Angular users claims that including JQuery solves … Continue reading AngularJS, Internet Explorer 9 and watch error
Tomcat/Scala: invalid byte tag in constant pool: 110
When deploying a Scala application on Tomcat 7 I got this weird error: invalid byte tag in constant pool: 110 from Tomcat's annotation scanning in the scala utils jar. There is this bug report that claims it's fixed, but it seems to still happen wit 7.0.53. Since the application doesn't rely on Tomcat's annotation scanning, … Continue reading Tomcat/Scala: invalid byte tag in constant pool: 110
Tomcat, Spring and memory leaks when undeploying or redeploying an web application
In this post I'll talk about a new kind of memory leak in Spring applications involving transaction management and initializing beans. About memory leaks when undeploying a web application While developing a web application with Spring and Tomcat I frequently run out of heap space. The web is full of stories about this. There is … Continue reading Tomcat, Spring and memory leaks when undeploying or redeploying an web application
Annotations, Java compiler and missing debugging information
So I play with my favorite ant build script and a day later nearly every annotation is broken: java.lang.IllegalStateException: No parameter name specified for argument of type [java.lang.String], and no parameter name information found in class file either. as far as the eye goes. What actually happened is that the new deployment skips debugging information … Continue reading Annotations, Java compiler and missing debugging information