After a publisher flushes a batch of messages the batch is (obviously) not received immediately by the service. While the batch remains pending it potentially consumes memory resources in the client (and/or the service).
Some applications may have constraints on the number of bytes and/or messages they can tolerate in this pending state, and may prefer to block or reject messages.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis page documents different versions of the \u003ccode\u003eMaxPendingMessagesOption\u003c/code\u003e for Google Cloud Pub/Sub.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available is 2.37.0-rc, with a range of prior releases going down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eMaxPendingMessagesOption\u003c/code\u003e controls the number of messages that can be pending after a flush, before the service receives them.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eMaxPendingMessagesOption\u003c/code\u003e's type is an alias of \u003ccode\u003estd::size_t\u003c/code\u003e, which represents the maximum number of pending messages.\u003c/p\u003e\n"],["\u003cp\u003eControlling the maximum pending messages is important because pending batches consume memory and some applications have limits on memory usage.\u003c/p\u003e\n"]]],[],null,[]]
