@Test
public void testAssignMigrations() {
servers.clear();
servers.put(
new TServerInstance(HostAndPort.fromParts("127.0.0.1", 1234), "a"), new FakeTServer());
servers.put(
new TServerInstance(HostAndPort.fromParts("127.0.0.1", 1235), "b"), new FakeTServer());
servers.put(
new TServerInstance(HostAndPort.fromParts("127.0.0.1", 1236), "c"), new FakeTServer());
List<KeyExtent> metadataTable = new ArrayList<KeyExtent>();
String table = "t1";
metadataTable.add(makeExtent(table, null, null));
table = "t2";
metadataTable.add(makeExtent(table, "a", null));
metadataTable.add(makeExtent(table, null, "a"));
table = "t3";
metadataTable.add(makeExtent(table, "a", null));
metadataTable.add(makeExtent(table, "b", "a"));
metadataTable.add(makeExtent(table, "c", "b"));
metadataTable.add(makeExtent(table, "d", "c"));
metadataTable.add(makeExtent(table, "e", "d"));
metadataTable.add(makeExtent(table, null, "e"));
Collections.sort(metadataTable);
TestDefaultLoadBalancer balancer = new TestDefaultLoadBalancer();
SortedMap<TServerInstance, TabletServerStatus> current =
new TreeMap<TServerInstance, TabletServerStatus>();
for (Entry<TServerInstance, FakeTServer> entry : servers.entrySet()) {
current.put(entry.getKey(), entry.getValue().getStatus(entry.getKey()));
}
assignTablets(metadataTable, servers, current, balancer);
// Verify that the counts on the tables are correct
Map<String, Integer> expectedCounts = new HashMap<String, Integer>();
expectedCounts.put("t1", 1);
expectedCounts.put("t2", 1);
expectedCounts.put("t3", 2);
checkBalance(metadataTable, servers, expectedCounts);
// Rebalance once
for (Entry<TServerInstance, FakeTServer> entry : servers.entrySet()) {
current.put(entry.getKey(), entry.getValue().getStatus(entry.getKey()));
}
// Nothing should happen, we are balanced
ArrayList<TabletMigration> out = new ArrayList<TabletMigration>();
balancer.getMigrations(current, out);
assertEquals(out.size(), 0);
// Take down a tabletServer
TServerInstance first = current.keySet().iterator().next();
current.remove(first);
FakeTServer remove = servers.remove(first);
// reassign offline extents
assignTablets(remove.extents, servers, current, balancer);
checkBalance(metadataTable, servers, null);
}
@Test
public void testUnevenAssignment2() {
servers.clear();
// make 26 servers
for (char c : "abcdefghijklmnopqrstuvwxyz".toCharArray()) {
String cString = Character.toString(c);
HostAndPort fakeAddress = HostAndPort.fromParts("127.0.0.1", (int) c);
String fakeInstance = cString;
TServerInstance tsi = new TServerInstance(fakeAddress, fakeInstance);
FakeTServer fakeTServer = new FakeTServer();
servers.put(tsi, fakeTServer);
}
// put 60 tablets on 25 of them
List<Entry<TServerInstance, FakeTServer>> shortList =
new ArrayList<Entry<TServerInstance, FakeTServer>>(servers.entrySet());
Entry<TServerInstance, FakeTServer> shortServer = shortList.remove(0);
int c = 0;
for (int i = 0; i < 60; i++) {
for (Entry<TServerInstance, FakeTServer> entry : shortList) {
entry.getValue().extents.add(makeExtent("t" + c, null, null));
}
}
// put 10 on the that short server:
for (int i = 0; i < 10; i++) {
shortServer.getValue().extents.add(makeExtent("s" + i, null, null));
}
TestDefaultLoadBalancer balancer = new TestDefaultLoadBalancer();
Set<KeyExtent> migrations = Collections.emptySet();
int moved = 0;
// balance until we can't balance no more!
while (true) {
List<TabletMigration> migrationsOut = new ArrayList<TabletMigration>();
balancer.balance(getAssignments(servers), migrations, migrationsOut);
if (migrationsOut.size() == 0) break;
for (TabletMigration migration : migrationsOut) {
if (servers.get(migration.oldServer).extents.remove(migration.tablet)) moved++;
servers.get(migration.newServer).extents.add(migration.tablet);
}
}
// average is 58, with 2 at 59: we need 48 more moved to the short server
assertEquals(48, moved);
}
private void assignTablets(
List<KeyExtent> metadataTable,
Map<TServerInstance, FakeTServer> servers,
SortedMap<TServerInstance, TabletServerStatus> status,
TestDefaultLoadBalancer balancer) {
// Assign tablets
for (KeyExtent extent : metadataTable) {
TServerInstance assignment = balancer.getAssignment(status, extent, null);
assertNotNull(assignment);
assertFalse(servers.get(assignment).extents.contains(extent));
servers.get(assignment).extents.add(extent);
}
}
@Test
public void testUnevenAssignment() {
servers.clear();
for (char c : "abcdefghijklmnopqrstuvwxyz".toCharArray()) {
String cString = Character.toString(c);
HostAndPort fakeAddress = HostAndPort.fromParts("127.0.0.1", (int) c);
String fakeInstance = cString;
TServerInstance tsi = new TServerInstance(fakeAddress, fakeInstance);
FakeTServer fakeTServer = new FakeTServer();
servers.put(tsi, fakeTServer);
fakeTServer.extents.add(makeExtent(cString, null, null));
}
// Put more tablets on one server, but not more than the number of servers
Entry<TServerInstance, FakeTServer> first = servers.entrySet().iterator().next();
first.getValue().extents.add(makeExtent("newTable", "a", null));
first.getValue().extents.add(makeExtent("newTable", "b", "a"));
first.getValue().extents.add(makeExtent("newTable", "c", "b"));
first.getValue().extents.add(makeExtent("newTable", "d", "c"));
first.getValue().extents.add(makeExtent("newTable", "e", "d"));
first.getValue().extents.add(makeExtent("newTable", "f", "e"));
first.getValue().extents.add(makeExtent("newTable", "g", "f"));
first.getValue().extents.add(makeExtent("newTable", "h", "g"));
first.getValue().extents.add(makeExtent("newTable", "i", null));
TestDefaultLoadBalancer balancer = new TestDefaultLoadBalancer();
Set<KeyExtent> migrations = Collections.emptySet();
int moved = 0;
// balance until we can't balance no more!
while (true) {
List<TabletMigration> migrationsOut = new ArrayList<TabletMigration>();
balancer.balance(getAssignments(servers), migrations, migrationsOut);
if (migrationsOut.size() == 0) break;
for (TabletMigration migration : migrationsOut) {
if (servers.get(migration.oldServer).extents.remove(migration.tablet)) moved++;
servers.get(migration.newServer).extents.add(migration.tablet);
}
}
assertEquals(8, moved);
}