Allan Yang created HBASE-20679:
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Summary: Add the ability to compile JSP dynamically in Jetty
Key: HBASE-20679
URL: https://issues.apache.org/jira/browse/HBASE-20679
Project: HBase
Issue Type: New Feature
Affects Versions: 2.0.0
Reporter: Allan Yang
Assignee: Allan Yang
Fix For: 3.0.0
As discussed in HBASE-20617, adding the ability to dynamically compile jsp
enable us to do some hot fix.
For example, several days ago, in our testing HBase-2.0 cluster, procedureWals
were corrupted due to some unknown reasons. After restarting the cluster, since
some procedures(AssignProcedure for example) were corrupted and couldn't be
replayed. Some regions were stuck in RIT forever. We couldn't use HBCK since it
haven't support AssignmentV2 yet. As a matter of fact, the namespace region was
not online, so the master was not inited, we even couldn't use shell command
like assign/move. But, we wrote a jsp and fix this issue easily. The jsp file
is like this:
{code:java}
<%
String action = request.getParameter("action");
HMaster master = (HMaster)getServletContext().getAttribute(HMaster.MASTER);
List<RegionInfo> offlineRegionsToAssign = new ArrayList<>();
List<RegionStates.RegionStateNode> regionRITs = master.getAssignmentManager()
.getRegionStates().getRegionsInTransition();
for (RegionStates.RegionStateNode regionStateNode : regionRITs) {
// if regionStateNode don't have a procedure attached, but meta state shows
// this region is in RIT, that means the previous procedure may be corrupted
// we need to create a new assignProcedure to assign them
if (!regionStateNode.isInTransition()) {
offlineRegionsToAssign.add(regionStateNode.getRegionInfo());
out.println("RIT region:" + regionStateNode);
}
}
// Assign offline regions. Uses round-robin.
if ("fix".equals(action) && offlineRegionsToAssign.size() > 0) {
master.getMasterProcedureExecutor().submitProcedures(master.getAssignmentManager().
createRoundRobinAssignProcedures(offlineRegionsToAssign));
} else {
out.println("use ?action=fix to fix RIT regions");
}
%>
{code}
Above it is only one example we can do if we have the ability to compile jsp
dynamically. We think it is very useful.
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