Installing plugins without restart don't work in case if non-refreshable extension is activated. In my case I had https://wiki.jenkins-ci.org/display/JENKINS/Persona+Plugin installed, and received following exception:
hudson.util.IOException2: Failed to dynamically deploy this plugin
at hudson.model.UpdateCenter$InstallationJob._run(UpdateCenter.java:1137)
at hudson.model.UpdateCenter$DownloadJob.run(UpdateCenter.java:955)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: hudson.util.IOException2: Failed to install build-name-setter-plugin plugin
at hudson.PluginManager.dynamicLoad(PluginManager.java:365)
at hudson.model.UpdateCenter$InstallationJob._run(UpdateCenter.java:1133)
... 7 more
Caused by: jenkins.ExtensionRefreshException: hudson.plugins.persona.xml.XmlPersonaFinder@1664d71 doesn't support refresh
at jenkins.model.Jenkins.refreshExtensions(Jenkins.java:1970)
at hudson.PluginManager.dynamicLoad(PluginManager.java:358)
... 8 more
@Gavriil
And so this plugin currently says that its extension is not refreshable and you hope that it can be installed without restarting?
I would say that something like this, saying that it can not be refreshed and so that it can not be installed without restarting is expected.
In fact, if this plugin and the update-center can not do that, they should certainly say it.
What do you expect instead?