[tidbx]tiflash cn oom when run tpch with tiflash columnar

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

tiflash-cn：2 * replica-12c64g
1, restore tpch data
/br restore db --db tpcc --pd tc-pd.ha-test-tiflash-with-columnar-tps-8174843-1-705:2379 --storage "s3://qe-testing/nfs/tiflash/ch-2k-flash2-collation?access-key=xxxxxx&secret-access-key=xxxxxx&endpoint=http%3a%2f%2fks3-cn-beijing-internal.ksyuncs.com&force-path-style=false&region=Beijing&provider=ks" --keyspace-name keyspace_a --send-credentials-to-tikv=true --check-requirements=false --checksum=false --tikv-max-restore-concurrency=16
2，alter database tpcc set tiflash replica 1 and wait AVAILABLE and PROGRESS are 1
3，run tpch
go-tpc ch run -D tpcc --host tc-tidb.ha-test-tiflash-with-columnar-tps-8174843-1-705 -P4000 --warehouses 2000 -T 32 --acThreads 1 --queries "q1,q2,q3,q4,q5,q6,q7,q8,q9,q10,q11,q12,q13,q14,q15,q16,q17,q18,q19,q20,q21,q22" --ignore-error '2013,1213,1205,8022,8028,9004,9007,1062,1105' --time 36000m --user root --interval '10s'

2. What did you expect to see? (Required)

no oom

3. What did you see instead (Required)

one of tiflash cn oom

4. What is your TiFlash version? (Required)

sh-5.1# /tiflash/tiflash version
TiFlash
Release Version: v9.0.0-beta.2.pre-200-g3d986e3de
Edition: Enterprise
Git Commit Hash: 3d986e3dedbf7ead0db13547ffdf2c24442276f1
Git Branch: HEAD
UTC Build Time: 2026-07-16 10:50:36
Enable Features: jemalloc sm4(GmSSL) mem-profiling avx2 avx512 unwind thinlto next-gen columnar hnsw.l2=skylake hnsw.cosine=skylake vec.l2=skylake vec.cos=skylake
Profile: RELWITHDEBINFO
Compiler: clang++ 17.0.6

TiFlash Columnar Hub
Git Commit Hash: eb32cf11d43a6bff9e51ecccb7f1f88862c70d70
Rust Version: rustc 1.95.0-nightly (842bd5be2 2026-01-29)
Prometheus Prefix: tiflash_proxy_
Profile: release
sh-5.1#