Thank you all for the comments, I got the point. Raised that issue because
in some of our tests we are using manual advance for the clock and that was
working just fine in 1.x releases (so create table operation was atomic
from this perspective). And that stops working with AMv2. Of course, we can
deal with it by using auto incremental edge, but my main concern was that
for a simple operation as create table we may run in the situation where
negative clock adjustment happen by ntpd/whatever because of time drift
which may (and usually) happen in a hypervisor environment (HyperV, KVM,
VMWare - they all have that issue under a heavy load). But it seems that
the master will retry the subprocedure and eventually it will be completed
(tried the same test with slow updated clock). I will raise the jira as
nice to have.
Thanks,
Sergey
On Wed, Jan 3, 2018 at 8:00 AM, stack <saint....@gmail.com> wrote:
> Stalling environmentedge as is done here does not work. In various areas in
> internals we expect the clock to advance. This is not particular to AMv2.
>
> As per Appy, we need HLC generally (it is almost there but needs some
> concentrated effort to carry it the last few yards).
>
> For AMv2, we have a single actor--the Master-- so we should be able to put
> up simple checks that we have an advancing clock.
>
> Please make an issue Sergey and we'll have a go at it. Thanks for raising
> this issue.
>
> S
>
> On Jan 2, 2018 5:58 PM, "Sergey Soldatov" <sergeysolda...@gmail.com>
> wrote:
>
> > Hi,
> > Not sure whether we may consider that as a bug, but I found an
> interesting
> > dependency of AM2 on clock advancing. A simple operation such as create
> > table is unable to perform with the same current_time value:
> >
> > public void testCreateTable() throws IOException {
> > EnvironmentEdgeManager.injectEdge(new EnvironmentEdge() {
> > volatile int curTime = 1000;
> >
> > @Override
> > public long currentTime() {
> >
> > return curTime;
> > }
> > });
> > final TableName tableName = TableName.valueOf("test");
> > TEST_UTIL.createTable(tableName, HConstants.CATALOG_FAMILY).close();
> > }
> >
> > and fails with a TableNotFound exception. The reason is that between
> > transitions we get table information from meta using Get with the
> exclusive
> > current timestamp. Could it be a potential problem (i.e. the system
> capable
> > to execute all that transition stuff in less than 1 ms)?
> >
> > Thanks,
> > Sergey
> >
>
