[Impala-ASF-CR] IMPALA-4480: zero length region must be as aligned as max align t

[Jim Apple (Code Review)]

Jim Apple has uploaded a new patch set (#2).

Change subject: IMPALA-4480: zero_length_region_ must be as aligned as 
max_align_t
..

IMPALA-4480: zero_length_region_ must be as aligned as max_align_t

MemPool::TryAllocateAligned returns memory that might be that aligned,
and it returns ::zero_length_region_ when called to allocate a
block of size 0.

While I'm here, do some things to make diagnosing test failures from
terminal output easier.

Change-Id: Ia31b27e38897f357478c4eedaab0c787e731b2d4
---
M be/src/runtime/mem-pool-test.cc
M be/src/runtime/mem-pool.h
M bin/run-backend-tests.sh
3 files changed, 8 insertions(+), 5 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/62/5062/2
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ia31b27e38897f357478c4eedaab0c787e731b2d4
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Jim Apple 
Gerrit-Reviewer: Dan Hecht 
Gerrit-Reviewer: Tim Armstrong 

[Impala-ASF-CR] IMPALA-4456: Change query exec state lock to a reader-writer lock

[Sailesh Mukil (Code Review)]

Sailesh Mukil has posted comments on this change.

Change subject: IMPALA-4456: Change query_exec_state_lock_ to a reader-writer 
lock
..


Patch Set 3:

> Once concern I have is about fairness. It's pretty critical that
 > writers don't get starved out of this lock because that prevents
 > queries from starting or finishing.
 > 
 > If there's enough demand for the reader-side of the lock such that
 > there's really no period at which the lock is free for writers, I
 > can see a starvation situation happening.
 > 
 > This doesn't happen right now because all once the lock is
 > released, there is always a period (however small) where the lock
 > is available for taking. You might need to think about an external
 > mechanism to prevent new readers from taking the lock when a writer
 > is waiting. That would make things more complicated, so let me know
 > if you have any better ideas.

Kudu has a RW lock that has a 'prefer writer' option.
https://github.com/apache/kudu/blob/0ce5ba594412de4365625485ea7b3c1ee21bf28d/src/kudu/util/rw_mutex.cc#L63

This will however starve readers once there are a steady stream of writers. But 
I don't think that should be a big issue because we will have writers only 
while registering or unregistering a query. So the no. writers on this lock is 
2x no. of queries on that coordinator, which is much less than the number of 
readers.

-- 
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Gerrit-MessageType: comment
Gerrit-Change-Id: I790a95e7179f07aa7ba188d5422c5e054353ba0b
Gerrit-PatchSet: 3
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Sailesh Mukil 
Gerrit-Reviewer: Henry Robinson 
Gerrit-Reviewer: Sailesh Mukil 
Gerrit-HasComments: No

[Impala-ASF-CR] IMPALA-4434: In Python, ''.split('\n') is [''], which has length 1

[Jim Apple (Code Review)]

Jim Apple has uploaded a new change for review.

  http://gerrit.cloudera.org:8080/5061

Change subject: IMPALA-4434: In Python, ''.split('\n') is [''], which has 
length 1
..

IMPALA-4434: In Python, ''.split('\n') is [''], which has length 1

This test simply may have never been run in GMT or UTC - it appears to
have an easy-to-make off-by-one error.

Change-Id: Iac4943085b0693deb380499cd0e141eb672bead8
---
M tests/custom_cluster/test_hive_parquet_timestamp_conversion.py
1 file changed, 4 insertions(+), 2 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/61/5061/1
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Iac4943085b0693deb380499cd0e141eb672bead8
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Jim Apple