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Type:
Bug
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Resolution: Unresolved
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: Internal Code
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Labels:None
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Service Arch
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ALL
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Hedging is controlled by the following server parameter, settable at both startup and runtime:
server_parameters:
readHedgingMode:
description: >-
Enables hedged reads.
set_at: [ startup, runtime ]
cpp_class:
name: HedgingModeServerParameter
The parameter is mapped to a global atomic, defined here and initialized to enabled:
AtomicWord<ReadHedgingMode> gReadHedgingMode{ReadHedgingMode::kOn};
This server parameter, along with other mongos-specific parameters (e.g., loadBalancerPort), is packed with async_requests_sender:
env.Library(
target='async_requests_sender',
source=[
'async_requests_sender.cpp',
],
LIBDEPS=[
...
'mongos_server_parameters',
],
LIBDEPS_PRIVATE=[
'$BUILD_DIR/mongo/executor/hedge_options_util',
],
)
However, there are non-mongos compilation units that link against this target. For example, the following makes hedging and other mongos-specific behavior available for mongod servers:
env.Library(
target='sharded_agg_helpers',
...
LIBDEPS=[
...
'$BUILD_DIR/mongo/s/async_requests_sender',
...
],
)
- is related to
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- Closed
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