I think you are using Servlet. Try this following code with init() method of servlet.
container = new CoreContainer(solrDir);
container.load();
server = new EmbeddedSolrServer(container, "collection1");
solrParams = new ModifiableSolrParams();
Reason: When ever servlet is load initialized, every time it creates container object and server object which is already using collection1 so that why is raises error of write.lock