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Updated the shared memory design #8

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jayant07-yb pushed a commit that referenced this pull request Dec 2, 2022
…e image

Summary:
We observed a crash while running TPCC workload with CDCSDK enabled.
The stack trace is:

```
(gdb) bt
#0  0x0000557f25b11910 in yb::DatumMessagePB::MergeFrom(yb::DatumMessagePB const&) ()
#1  0x0000557f258a41ef in yb::cdc::PopulateBeforeImage(std::__1::shared_ptr<yb::tablet::TabletPeer> const&, yb::ReadHybridTime const&, yb::cdc::RowMessage*, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::docdb::SubDocKey const&, yb::Schema const&, unsigned int) ()
#2  0x0000557f258a7304 in yb::cdc::PopulateCDCSDKIntentRecord(yb::OpId const&, yb::StronglyTypedUuid<yb::TransactionId_Tag> const&, std::__1::vector<yb::docdb::IntentKeyValueForCDC, std::__1::allocator<yb::docdb::IntentKeyValueForCDC> > const&, yb::cdc::StreamMetadata const&, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::cdc::GetChangesResponsePB*, yb::ScopedTrackedConsumption*, unsigned int*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, yb::Schema*, unsigned int, unsigned long const&) ()
#3  0x0000557f258aaa27 in yb::cdc::ProcessIntents(yb::OpId const&, yb::StronglyTypedUuid<yb::TransactionId_Tag> const&, yb::cdc::StreamMetadata const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::cdc::GetChangesResponsePB*, yb::ScopedTrackedConsumption*, yb::cdc::CDCSDKCheckpointPB*, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::vector<yb::docdb::IntentKeyValueForCDC, std::__1::allocator<yb::docdb::IntentKeyValueForCDC> >*, yb::docdb::ApplyTransactionState*, yb::client::YBClient*, std::__1::shared_ptr<yb::Schema>*, unsigned int*, unsigned long const&) ()
#4  0x0000557f258b00c1 in yb::cdc::GetChangesForCDCSDK(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, yb::cdc::CDCSDKCheckpointPB const&, yb::cdc::StreamMetadata const&, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::shared_ptr<yb::MemTracker> const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::client::YBClient*, yb::consensus::ReplicateMsgsHolder*, yb::cdc::GetChangesResponsePB*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::shared_ptr<yb::Schema>*, unsigned int*, yb::OpId*, long*, std::__1::chrono::time_point<yb::CoarseMonoClock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) ()
#5  0x0000557f2586c448 in yb::cdc::CDCServiceImpl::GetChanges(yb::cdc::GetChangesRequestPB const*, yb::cdc::GetChangesResponsePB*, yb::rpc::RpcContext) ()
#6  0x0000557f25908246 in std::__1::__function::__func<yb::cdc::CDCServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_3, std::__1::allocator<yb::cdc::CDCServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_3>, void (std::__1::shared_ptr<yb::rpc::InboundCall>)>::operator()(std::__1::shared_ptr<yb::rpc::InboundCall>&&) ()
#7  0x0000557f2590a6af in yb::cdc::CDCServiceIf::Handle(std::__1::shared_ptr<yb::rpc::InboundCall>) ()
#8  0x0000557f26227a1e in yb::rpc::ServicePoolImpl::Handle(std::__1::shared_ptr<yb::rpc::InboundCall>) ()
#9  0x0000557f2616db2f in yb::rpc::InboundCall::InboundCallTask::Run() ()
#10 0x0000557f26236583 in yb::rpc::(anonymous namespace)::Worker::Execute() ()
#11 0x0000557f268698cf in yb::Thread::SuperviseThread(void*) ()
#12 0x00007fa6fce89694 in ?? ()
#13 0x0000000000000000 in ?? ()
```

The problem is in the method: PopulateBeforeImage
When we drop a column, the the row won't have data for the dropped column, and hence will not be added to the "old_tuple" member of RowMessage. This will mean the size of "old_tuple" does not match the number of columns in the schema.
Which means this line: "row_message->old_tuple(static_cast<int>(index))" could lead to an out of bounds exception.
Instead,  now we are keeping track of the found columns in the row.

Test Plan: Running existing ctests

Reviewers: srangavajjula, sdash, skumar

Reviewed By: sdash, skumar

Differential Revision: https://phabricator.dev.yugabyte.com/D21338
@jayant07-yb jayant07-yb force-pushed the Handling_exceptions_session_parameters branch from 78cb174 to 26a07a4 Compare December 7, 2022 08:37
jayant07-yb pushed a commit that referenced this pull request Dec 7, 2022
…e image

Summary:
We observed a crash while running TPCC workload with CDCSDK enabled.
The stack trace is:

```
(gdb) bt
#0  0x0000557f25b11910 in yb::DatumMessagePB::MergeFrom(yb::DatumMessagePB const&) ()
#1  0x0000557f258a41ef in yb::cdc::PopulateBeforeImage(std::__1::shared_ptr<yb::tablet::TabletPeer> const&, yb::ReadHybridTime const&, yb::cdc::RowMessage*, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::docdb::SubDocKey const&, yb::Schema const&, unsigned int) ()
#2  0x0000557f258a7304 in yb::cdc::PopulateCDCSDKIntentRecord(yb::OpId const&, yb::StronglyTypedUuid<yb::TransactionId_Tag> const&, std::__1::vector<yb::docdb::IntentKeyValueForCDC, std::__1::allocator<yb::docdb::IntentKeyValueForCDC> > const&, yb::cdc::StreamMetadata const&, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::cdc::GetChangesResponsePB*, yb::ScopedTrackedConsumption*, unsigned int*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, yb::Schema*, unsigned int, unsigned long const&) ()
#3  0x0000557f258aaa27 in yb::cdc::ProcessIntents(yb::OpId const&, yb::StronglyTypedUuid<yb::TransactionId_Tag> const&, yb::cdc::StreamMetadata const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::cdc::GetChangesResponsePB*, yb::ScopedTrackedConsumption*, yb::cdc::CDCSDKCheckpointPB*, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::vector<yb::docdb::IntentKeyValueForCDC, std::__1::allocator<yb::docdb::IntentKeyValueForCDC> >*, yb::docdb::ApplyTransactionState*, yb::client::YBClient*, std::__1::shared_ptr<yb::Schema>*, unsigned int*, unsigned long const&) ()
#4  0x0000557f258b00c1 in yb::cdc::GetChangesForCDCSDK(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, yb::cdc::CDCSDKCheckpointPB const&, yb::cdc::StreamMetadata const&, std::__1::shared_ptr<yb::tablet::TabletPeer> const&, std::__1::shared_ptr<yb::MemTracker> const&, std::__1::unordered_map<unsigned int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > > const&, std::__1::unordered_map<unsigned int, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> >, std::__1::hash<unsigned int>, std::__1::equal_to<unsigned int>, std::__1::allocator<std::__1::pair<unsigned int const, std::__1::vector<yb::master::PgAttributePB, std::__1::allocator<yb::master::PgAttributePB> > > > > const&, yb::client::YBClient*, yb::consensus::ReplicateMsgsHolder*, yb::cdc::GetChangesResponsePB*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >*, std::__1::shared_ptr<yb::Schema>*, unsigned int*, yb::OpId*, long*, std::__1::chrono::time_point<yb::CoarseMonoClock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> > >) ()
#5  0x0000557f2586c448 in yb::cdc::CDCServiceImpl::GetChanges(yb::cdc::GetChangesRequestPB const*, yb::cdc::GetChangesResponsePB*, yb::rpc::RpcContext) ()
#6  0x0000557f25908246 in std::__1::__function::__func<yb::cdc::CDCServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_3, std::__1::allocator<yb::cdc::CDCServiceIf::InitMethods(scoped_refptr<yb::MetricEntity> const&)::$_3>, void (std::__1::shared_ptr<yb::rpc::InboundCall>)>::operator()(std::__1::shared_ptr<yb::rpc::InboundCall>&&) ()
#7  0x0000557f2590a6af in yb::cdc::CDCServiceIf::Handle(std::__1::shared_ptr<yb::rpc::InboundCall>) ()
#8  0x0000557f26227a1e in yb::rpc::ServicePoolImpl::Handle(std::__1::shared_ptr<yb::rpc::InboundCall>) ()
#9  0x0000557f2616db2f in yb::rpc::InboundCall::InboundCallTask::Run() ()
#10 0x0000557f26236583 in yb::rpc::(anonymous namespace)::Worker::Execute() ()
#11 0x0000557f268698cf in yb::Thread::SuperviseThread(void*) ()
#12 0x00007fa6fce89694 in ?? ()
#13 0x0000000000000000 in ?? ()
```

The problem is in the method: PopulateBeforeImage
When we drop a column, the the row won't have data for the dropped column, and hence will not be added to the "old_tuple" member of RowMessage. This will mean the size of "old_tuple" does not match the number of columns in the schema.
Which means this line: "row_message->old_tuple(static_cast<int>(index))" could lead to an out of bounds exception.
Instead,  now we are keeping track of the found columns in the row.

Test Plan: Running existing ctests

Reviewers: srangavajjula, sdash, skumar

Reviewed By: sdash, skumar

Differential Revision: https://phabricator.dev.yugabyte.com/D21338
@jayant07-yb jayant07-yb force-pushed the Shared_Memory_Redesign branch from a941745 to ad9a388 Compare December 7, 2022 09:00
@jayant07-yb jayant07-yb closed this Dec 7, 2022
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