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• Motivation
• Description
• Risks and Assumptions
• Discussion Links
• Reference Links
• Tickets

Motivation

Tracing provides information useful for debugging that both helps with regular, daily-basic system monitoring and with incidents analysis. Within the scope of Apache Ignite almost every process or sub-system could be traced including:

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• 1 byte: special flags;

  • First byte of the serializedSpan is reserved for special flags

• 1 bytes: spi type;

  • In order to match whether span was serialized with the spi that is used on the node that is going to deserialize it.

• 2 bytes: major protocol version;

  • Spans are considered as incompatible in case of different major protocol versions;

• 2 bytes: minor protocol version;

  • Should be incremented in case of adding new fields, etc. Within the scope of the same major protocol version and different minor protocol versions spans are considered to be compatible.

• 4 bytes: spi specific serialized span length;

• n bytes: spi specific serialized span body;

• 4 bytes: span type

• 4 bytes included scopes size;

• 2 * included scopes size: included scopes items one by one;

Trace Tree Example

Bellow there's an example of trace generated by pessimistic serializable transaction.

Image Added

Risks and Assumptions

• Performance drop. So careful benchmarking is requires and probably lots of optimizations.
• Spans inconsistencies during rolling upgrade if nodes have different versions of TracingManagers or Tracing Service Provider Interfaces. Span Serialization protocol must take this into account.

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