Sean Busbey created ACCUMULO-4556:
-------------------------------------
Summary: Monitor shows stack trace for NPE while viewing table
details for accumulo.root if tablet is offline
Key: ACCUMULO-4556
URL: https://issues.apache.org/jira/browse/ACCUMULO-4556
Project: Accumulo
Issue Type: Bug
Components: monitor
Affects Versions: 1.8.0, 1.7.2, 1.7.1
Reporter: Sean Busbey
AFAICT this is a problem in atleast 1.6.0 - current master (2.0-SNAPSHOT)
Noticed this while debugging a cluster with offline root tablet:
monitor -> Tables -> (shows accumulo.root with 1 offline tablet) ->
accumulo.root ->
{code}
java.lang.NullPointerException
at java.util.TreeMap.compare(TreeMap.java:1188)
at java.util.TreeMap.put(TreeMap.java:531)
at java.util.TreeSet.add(TreeSet.java:255)
at
org.apache.accumulo.monitor.servlets.TablesServlet.doTableDetails(TablesServlet.java:152)
at
org.apache.accumulo.monitor.servlets.TablesServlet.pageBody(TablesServlet.java:75)
at
org.apache.accumulo.monitor.servlets.BasicServlet.doGet(BasicServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:767)
at
org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:228)
at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
{code}
Looking at master branch our handling in TablesServlet looks like
{code}
private void doTableDetails(HttpServletRequest req, StringBuilder sb,
Map<String,String> tidToNameMap, String tableId) {
String displayName = Tables.getPrintableTableNameFromId(tidToNameMap,
tableId);
Instance instance = Monitor.getContext().getInstance();
TreeSet<String> locs = new TreeSet<>();
if (RootTable.ID.equals(tableId)) {
locs.add(instance.getRootTabletLocation());
} else {
...
{code}
The Instance API doesn't say it, but all of our current implementations return
{{null}} for {{getRootTabletLocation}} when the root tablet is offline. Since
we create {{locs}} with the empty constructor, it uses natural ordering and
doesn't allow {{null}} members, so things explode.
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