fix: replace module-level mutable tables with per-call allocation#13369
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nic-6443 merged 3 commits intoMay 14, 2026
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Several plugins and routers declared `local tbl = {}` at module scope
and reused the same table across coroutines via `core.table.clear()`.
When a function yields (e.g. `ctx.var[...]` lookup or shdict op),
another concurrent request on the same worker can re-enter and mutate
the shared table, causing cross-request state pollution.
Affected high-risk sites (yield in function body):
- prometheus/exporter.lua: inner_tab_arr in gen_arr(), extra_labels_tbl
in extra_labels() — use per-call local table
- proxy-cache/util.lua: tmp in generate_complex_value() — use tablepool
- redirect.lua: tmp in concat_new_uri() — use tablepool
Affected low-risk sites (preventive, no current yield):
- api_router.lua: match_opts in match() — use tablepool
- control/router.lua: match_opts in match() — use tablepool
- stream/router/ip_port.lua: match_opts in match() — use tablepool
This follows the same fix pattern as the historical radixtree_host_uri
route-mismatch fix (PR apache#10198).
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Pull request overview
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This PR removes module-level mutable tables that were reused across concurrent requests (coroutines) and replaces them with per-call allocations or core.tablepool.fetch/release to prevent cross-request state pollution when functions yield.
Changes:
- Replaced module-scope
match_optstables withcore.tablepool.fetch/releasein multiple routers. - Replaced module-scope temporary arrays in redirect/proxy-cache utilities with
core.tablepool.fetch/release. - Replaced reuse of module-scope tables in Prometheus exporter helpers with per-call table allocations.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| apisix/stream/router/ip_port.lua | Uses tablepool for match_opts during TLS router dispatch. |
| apisix/plugins/redirect.lua | Uses tablepool for URI segment concatenation temp table. |
| apisix/plugins/proxy-cache/util.lua | Uses tablepool for complex value concatenation temp table. |
| apisix/plugins/prometheus/exporter.lua | Switches helper tables to per-call allocations to avoid shared state. |
| apisix/control/router.lua | Uses tablepool for match_opts during control-plane route dispatch. |
| apisix/api_router.lua | Uses tablepool for match_opts during API router dispatch. |
Comments suppressed due to low confidence (2)
apisix/plugins/redirect.lua:1
tmpis released only on the normal path. If an exception is raised anywhere afterfetch(e.g., unexpected runtime error inside the loop/body), the pooled table will not be returned to the pool, which can degrade long-running worker behavior. Consider wrapping the body betweenfetchandreleasesocore.tablepool.release(...)is guaranteed to run even when an error occurs (then rethrow/propagate the error).
--
apisix/plugins/proxy-cache/util.lua:1
- Same pooling concern as in
redirect.lua: if any error occurs afterfetch(e.g., fromresolve_varor other runtime failures),tmpwill not be released back to the pool. Ensurecore.tablepool.release(...)executes on both success and error paths to avoid leaking pooled tables.
--
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Signed-off-by: Nic <[email protected]>
membphis
approved these changes
May 14, 2026
shreemaan-abhishek
approved these changes
May 14, 2026
AlinsRan
approved these changes
May 14, 2026
wistefan
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Jun 16, 2026
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Several plugins and routers declared
local tbl = {}at module scope and reused the same table across coroutines viacore.table.clear(). When a function yields (e.g.ctx.var[...]lookup or shdict op), another concurrent request on the same worker can re-enter and mutate the shared table, causing cross-request state pollution.Affected high-risk sites (yield in function body):
prometheus/exporter.lua:inner_tab_arringen_arr(),extra_labels_tblinextra_labels()— replaced with per-call local tableproxy-cache/util.lua:tmpingenerate_complex_value()— replaced withcore.tablepool.fetch/releaseredirect.lua:tmpinconcat_new_uri()— replaced withcore.tablepool.fetch/releaseAffected low-risk sites (preventive, no current yield):
api_router.lua:match_optsinmatch()— replaced withcore.tablepool.fetch/releasecontrol/router.lua:match_optsinmatch()— replaced withcore.tablepool.fetch/releasestream/router/ip_port.lua:match_optsinmatch()— replaced withcore.tablepool.fetch/releaseThis follows the same fix pattern as the historical radixtree_host_uri route-mismatch fix (PR #10198).